docs: update/annotate formerly experimental configs

[Meschreiber]

This PR removes the <ExperimentalFeature> annotation for two configs that are no longer experimental and adds a note for when they became generally available. I considered adding the following text to the note, but found it unnecessary.

Router configurations with telemetry.apollo.experimental_apollo_metrics_reference_mode will continue to work, but Apollo recommends updating the configuration to telemetry.apollo.metrics_reference_mode.

Happy to add it back if others deem it's helpful.

See #5807 for more info.

[github-actions]

@Meschreiber, please consider creating a changeset entry in /.changesets/. These instructions describe the process and tooling.

[router-perf]

CI performance tests

• connectors-const - Connectors stress test that runs with a constant number of users
• const - Basic stress test that runs with a constant number of users
• demand-control-instrumented - A copy of the step test, but with demand control monitoring and metrics enabled
• demand-control-uninstrumented - A copy of the step test, but with demand control monitoring enabled
• enhanced-signature - Enhanced signature enabled
• events - Stress test for events with a lot of users and deduplication ENABLED
• events_big_cap_high_rate - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity
• events_big_cap_high_rate_callback - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity using callback mode
• events_callback - Stress test for events with a lot of users and deduplication ENABLED in callback mode
• events_without_dedup - Stress test for events with a lot of users and deduplication DISABLED
• events_without_dedup_callback - Stress test for events with a lot of users and deduplication DISABLED using callback mode
• extended-reference-mode - Extended reference mode enabled
• large-request - Stress test with a 1 MB request payload
• no-tracing - Basic stress test, no tracing
• reload - Reload test over a long period of time at a constant rate of users
• step-jemalloc-tuning - Clone of the basic stress test for jemalloc tuning
• step-local-metrics - Field stats that are generated from the router rather than FTV1
• step-with-prometheus - A copy of the step test with the Prometheus metrics exporter enabled
• step - Basic stress test that steps up the number of users over time
• xlarge-request - Stress test with 10 MB request payload
• xxlarge-request - Stress test with 100 MB request payload

[bonnici]

The config rename will happen in v1.54.0, so we should use that as the version it became GA (and not merge this until then).

[Meschreiber]

This is merging into dev, so I think we can/should merge before the release, right?

[abernix]

Yes! We'll start 1.54.0 (as a release candidate) today and this will not land in our docs until next Tuesday when we finalize 1.54.0. 😄 I'll merge this to make sure it makes the cut. (It looks like the version was already raised to 1.54.0 in the text, which is totes right.)