ref(ci): Re-add ALWAYS_RUN_TESTS to selective test computing

[rbro112]

I had added an ALWAYS_RUN_TESTS config to compute-selective-tests.py in #112154 per Mark's request. At some point, compute-selective-tests.py was deleted and compute-sentry-selected-tests.py was added, but this ALWAYS_RUN_TESTS was not included.

Today, a test breakage slipped through on master that this ALWAYS_RUN_TESTS would've caught (Slack), this re-adds the tests to always run.

[rbro112]

• ref(ci): Re-add ALWAYS_RUN_TESTS to selective test computing #112930 👈 (View in Graphite)
• master

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[sentry]

Bug: Tests in ALWAYS_RUN_TESTS can be silently skipped if the file path is invalid, as they are filtered with Path.exists() without raising an error on failure.
_{Severity: HIGH}

Suggested Fix

Either exempt files in ALWAYS_RUN_TESTS from the Path.exists() check, or modify the logic to raise an error and fail the CI job if a test from this list is not found. This ensures that missing critical tests do not go unnoticed.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: .github/workflows/scripts/compute-sentry-selected-tests.py#L232-L235

Potential issue: The script ensures tests in `ALWAYS_RUN_TESTS` are always executed.
However, these tests are subjected to an existence check using `Path(f).exists()`. If a
test file from this list is renamed, deleted, or its relative path becomes invalid, it
is silently removed from the test suite. A debug message is logged, but the CI job does
not fail. This defeats the purpose of the `ALWAYS_RUN_TESTS` mechanism, as it could
allow breakages in critical tests to go unnoticed.