fix: content dialog styling is being applied to all dialogs

[micaelae]

Description

Problem: A scss change for preventing modal scrolling in the bridge experience was added and got unintentionally applied to all modals.

Solution: Nest the styling within the quotes-modal className

Related issues

Fixes: #28722

Manual testing steps

1. Visually inspect Swap token picker
2. Visually inspect tx "Speed up" and "Cancel" layout

Screenshots/Recordings

Before

See bug report screenshots

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• 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 format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). 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.

[metamaskbot]

Builds ready [73428fb]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7
  • common: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9
  • content-script: 0
  • offscreen: 0
  • ui: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1779 ± 70 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	1560	2244	1777	146	70
		domContentLoaded	1535	2204	1748	143	68
		load	1564	2249	1779	146	70
		domInteractive	25	68	37	12	6
		backgroundConnect	12	82	32	20	10
		firstReactRender	17	82	32	21	10
		getState	5	62	26	21	10
		initialActions	0	1	0	0	0
		loadScripts	1075	1637	1269	118	56
		setupStore	6	59	17	18	9
		uiStartup	1741	2497	1984	159	76

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 0 Bytes (0.00%)
• common: 0 Bytes (0.00%)