fix: fix test networks display for portfolio view (#28601)

<!--
Please submit this PR as a draft initially.
Do not mark it as "Ready for review" until the template has been
completely filled out, and PR status checks have passed at least once.
-->

## **Description**

This PR fixes the display in the asset page and in the main token list
when the price checker setting is off

[![Open in GitHub
Codespaces](https://github.com/codespaces/badge.svg)](https://codespaces.new/MetaMask/metamask-extension/pull/28601?quickstart=1)

## **Related issues**

Fixes: #28594

## **Manual testing steps**

1. Go to this page...
2.
3.

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

<!-- [screenshots/recordings] -->

### **After**


https://github.com/user-attachments/assets/a1213b6a-3f23-49f5-be15-a0b369b9016e


<!-- [screenshots/recordings] -->

## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've completed the PR template to the best of my ability
- [ ] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

ui/components/app/assets/token-cell/token-cell.tsx

@@ -84,17 +84,14 @@ export default function TokenCell({
     image;
 
   const secondaryThreshold = 0.01;
-
   // Format for fiat balance with currency style
-  const secondary = formatWithThreshold(
-    tokenFiatAmount,
-    secondaryThreshold,
-    locale,
-    {
-      style: 'currency',
-      currency: currentCurrency.toUpperCase(),
-    },
-  );
+  const secondary =
+    tokenFiatAmount === null
+      ? undefined
+      : formatWithThreshold(tokenFiatAmount, secondaryThreshold, locale, {
+          style: 'currency',
+          currency: currentCurrency.toUpperCase(),
+        });
 
   const primary = formatAmount(
     locale,

ui/components/app/assets/token-list/token-list.tsx

@@ -7,13 +7,15 @@ import { sortAssets } from '../util/sort';
 import {
   getCurrencyRates,
   getCurrentNetwork,
+  getIsTestnet,
   getMarketData,
   getNetworkConfigurationIdByChainId,
   getNewTokensImported,
   getPreferences,
   getSelectedAccount,
   getSelectedAccountNativeTokenCachedBalanceByChainId,
   getSelectedAccountTokensAcrossChains,
+  getShowFiatInTestnets,
   getTokenExchangeRates,
 } from '../../../../selectors';
 import { getConversionRate } from '../../../../ducks/metamask/metamask';
@@ -24,6 +26,8 @@ import { endTrace, TraceName } from '../../../../../shared/lib/trace';
 import { useTokenBalances } from '../../../../hooks/useTokenBalances';
 import { setTokenNetworkFilter } from '../../../../store/actions';
 import { useI18nContext } from '../../../../hooks/useI18nContext';
+import { useMultichainSelector } from '../../../../hooks/useMultichainSelector';
+import { getMultichainShouldShowFiat } from '../../../../selectors/multichain';
 
 type TokenListProps = {
   onTokenClick: (chainId: string, address: string) => void;
@@ -212,6 +216,18 @@ export default function TokenList({
     console.log(t('loadingTokens'));
   }
 
+  // Check if testnet
+  const isTestnet = useSelector(getIsTestnet);
+  const shouldShowFiat = useMultichainSelector(
+    getMultichainShouldShowFiat,
+    selectedAccount,
+  );
+  const isMainnet = !isTestnet;
+  // Check if show conversion is enabled
+  const showFiatInTestnets = useSelector(getShowFiatInTestnets);
+  const showFiat =
+    shouldShowFiat && (isMainnet || (isTestnet && showFiatInTestnets));
+
   return (
     <div>
       {sortedFilteredTokens.map((tokenData) => (
@@ -220,7 +236,7 @@ export default function TokenList({
           chainId={tokenData.chainId}
           address={tokenData.address}
           symbol={tokenData.symbol}
-          tokenFiatAmount={tokenData.tokenFiatAmount}
+          tokenFiatAmount={showFiat ? tokenData.tokenFiatAmount : null}
           image={tokenData?.image}
           isNative={tokenData.isNative}
           string={tokenData.string}

ui/pages/asset/components/asset-page.tsx

@@ -18,6 +18,8 @@ import {
   getCurrencyRates,
   getSelectedAccountNativeTokenCachedBalanceByChainId,
   getSelectedAccount,
+  getIsTestnet,
+  getShowFiatInTestnets,
 } from '../../../selectors';
 import {
   Display,
@@ -49,6 +51,8 @@ import CoinButtons from '../../../components/app/wallet-overview/coin-buttons';
 import { getIsNativeTokenBuyable } from '../../../ducks/ramps';
 import { calculateTokenBalance } from '../../../components/app/assets/util/calculateTokenBalance';
 import { useTokenBalances } from '../../../hooks/useTokenBalances';
+import { useMultichainSelector } from '../../../hooks/useMultichainSelector';
+import { getMultichainShouldShowFiat } from '../../../selectors/multichain';
 import { getPortfolioUrl } from '../../../helpers/utils/portfolio';
 import AssetChart from './chart/asset-chart';
 import TokenButtons from './token-buttons';
@@ -109,6 +113,17 @@ const AssetPage = ({
   const marketData = useSelector(getMarketData);
   const currencyRates = useSelector(getCurrencyRates);
 
+  const isTestnet = useSelector(getIsTestnet);
+  const shouldShowFiat = useMultichainSelector(
+    getMultichainShouldShowFiat,
+    selectedAccount,
+  );
+  const isMainnet = !isTestnet;
+  // Check if show conversion is enabled
+  const showFiatInTestnets = useSelector(getShowFiatInTestnets);
+  const showFiat =
+    shouldShowFiat && (isMainnet || (isTestnet && showFiatInTestnets));
+
   const nativeBalances: Record<Hex, Hex> = useSelector(
     getSelectedAccountNativeTokenCachedBalanceByChainId,
   ) as Record<Hex, Hex>;
@@ -254,7 +269,7 @@ const AssetPage = ({
           chainId={chainId}
           symbol={symbol}
           image={image}
-          tokenFiatAmount={tokenFiatAmount}
+          tokenFiatAmount={showFiat ? tokenFiatAmount : null}
           string={balance?.toString()}
         />
         <Box