CI: Run check-codestyle-rust as part of pre-merge-checks

[jcgruenhage]

Problem

When multiple changes are grouped in a merge group to be merged as part of the merge queue, the changes might individually pass check-codestyle-rust but not in their combined form.

Summary of changes

• Move check-codestyle-rust into a reusable workflow that is called from it's previous location in build_and_test.yml, and additionally call it from pre_merge_checks.yml. The additional call does not run on ARM, only x86, to ensure the merge queue continues being responsive.
• Trigger pre_merge_checks.yml on PRs that change any of the workflows running in pre_merge_checks.yml, so that we get feedback on those early an not only after trying to merge those changes.

[github-actions]

7304 tests run: 6934 passed, 0 failed, 370 skipped (full report)

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Flaky tests (4)

Postgres 17

• test_subscriber_synchronous_commit: release-x86-64
• test_nbtree_pagesplit_cycleid: release-arm64
• test_scrubber_physical_gc_ancestors[None]: debug-x86-64

Postgres 16

• test_timeline_copy[500000]: release-x86-64

Code coverage* (full report)

• functions: 32.8% (8154 of 24827 functions)
• lines: 48.1% (68272 of 142072 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
4bbf90d at 2025-01-15T11:26:00.872Z :recycle:}

[bayandin]

Looks good!