👷 fix performance benchmark CI and rename e2e setup script

[thomas-lebeau]

Motivation

The performance benchmark CI job was failing because yarn test:performance what trying to install playwright browsers which is unnecessary as they are prebuild in the CI image.

Changes

• Add yarn build and yarn build:apps steps to the performance-benchmark CI job so apps are built before running performance tests
• Remove the build steps from the test:performance npm script (they now live in CI, keeping the local script lean and avoiding a double-build)
• Rename test:e2e:init → test:e2e:setup for clarity; update all references in AGENTS.md, docs/TESTING.md, test/e2e/AGENTS.md, and test/e2e/playwright.config.ts

Test instructions

• Verify CI performance benchmark job passes after this change
• Locally, confirm yarn test:e2e:setup works as expected (same behavior as the old test:e2e:init)

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	172.04 KiB	172.04 KiB	0 B	0.00%	✅
Rum Profiler	7.88 KiB	7.88 KiB	0 B	0.00%	✅
Rum Recorder	21.09 KiB	21.09 KiB	0 B	0.00%	✅
Logs	54.64 KiB	54.64 KiB	0 B	0.00%	✅
Rum Slim	129.72 KiB	129.72 KiB	0 B	0.00%	✅
Worker	22.96 KiB	22.96 KiB	0 B	0.00%	✅

[datadog-prod-us1-4]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 76.81% (-0.02%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: b3bb065 | Docs | Datadog PR Page | Give us feedback!}