Use official st workflow

[cbeauchesne]

What does this PR do?
Use the official system-tests workflow

• remove this big todo list in comment in new workflow file
• Include parametric scenario
• uncomment the schedule trigger in this file
• uncomment the pull request trigger in this file
• delete .github/forced-tests-list.json (and check if .github/forced-tests-list.cfg is up-to-date)
• update docs/ForcingSystemTests.md
• update the cleanup task in the release process that cleans forced tests
  • Merge https://github.com/DataDog/fast_castle/pull/50 after this PR

Change log entry
None.

Additional Notes:

How to test the change?

[github-actions]

Thank you for updating Change log entry section 👏

^{Visited at: 2025-08-25 09:55:33 UTC}

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-08-25 10:35:43

Comparing candidate commit 2261c6f in PR branch cbeauchesne/use-official-st-workflow with baseline commit 319db66 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 44 metrics, 2 unstable metrics.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.54%. Comparing base (319db66) to head (2261c6f).
⚠️ Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4866      +/-   ##
==========================================
- Coverage   97.55%   97.54%   -0.02%     
==========================================
  Files        1507     1507              
  Lines       89790    89789       -1     
  Branches     4755     4755              
==========================================
- Hits        87598    87584      -14     
- Misses       2192     2205      +13     

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[ivoanjo]

Nice! I'm happy we finally got to this point. I think this is one case where it'd be nice to get a second review on top of mine before we merge it so I dropped a note on the channel about it.

[marcotc]

@cbeauchesne when this PR is ready to merge, invoke the mergequeue bot!

[cbeauchesne]

/merge

[dd-devflow-routing-codex]

View all feedbacks in Devflow UI.

2025-08-27 14:38:10 UTC ℹ️ Start processing command /merge

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2025-08-27 14:38:29 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 32m (p90).

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2025-08-27 15:14:45 UTC ℹ️ MergeQueue: This merge request was merged