Report timespans for promotion and prewarm

[myrrc]

• Return sub-actions time spans for prewarm, prewarm offload, and promotion in http handlers.
• Set synchronous_standby_names=walproposer for promoted endpoints. Otherwise, walproposer on promoted standby ignores reply from safekeeper and is stuck on lsn COMMIT eternally.

[github-actions]

9108 tests run: 8455 passed, 0 failed, 653 skipped (full report)

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Flaky tests (4)

Postgres 17

• test_replica_query_race: release-arm64-with-lfc
• test_tx_abort_with_many_relations[v2]: release-arm64-without-lfc

Postgres 15

• test_lfc_prefetch: release-arm64-with-lfc

Postgres 14

• test_lfc_prewarm_cancel: release-arm64-with-lfc

Code coverage* (full report)

• functions: 34.7% (8840 of 25453 functions)
• lines: 45.8% (71636 of 156549 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
887bea6 at 2025-07-31T10:47:10.477Z :recycle:}

[tristan957]

This would have been easier to review in smaller PRs. It seems like there are 3 things going on with this one PR which you listed in the original description. Can you break it apart?

[myrrc]

(3) is a one-liner, so I'll separate prewarm cancellation

[tristan957]

Also,

Return sub-actions time spans for prewarm, prewarm offload, and promotion in http handlers.

Would be good to separate out. That will leave this PR in a much better state for a better review.

[myrrc]

@tristan957 #12785

[myrrc]

Would be good to separate out. That will leave this PR in a much better state for a better review.

Timespans reporting and fix for spec application are fine in a single PR