pageserver: enable virtual_file_io_mode=direct in CI by default

[yliang412]

Closes #9713

Problem

We have virtual_file_io_mode config, but we don't set it in CI. We should enable virtual_file_io_mode=direct for both regression tests and benchmarks.

Summary of changes

Config handling are done in the same way as what we did for virtual_file_io_engine.

• Unit test setting are done through NEON_PAGESERVER_IOMODE, if not set, use virtual_file_io_mode=direct.
• Set PAGESERVER_VIRTUAL_FILE_IO_MODE: direct in regression tests and benchmarks
• For deployment that does not have virtual_file_io_mode config set, still use buffered io.

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

5418 tests run: 5169 passed, 6 failed, 243 skipped (full report)

---

Failures on Postgres 17

• test_tx_abort_with_many_relations: release-arm64

Failures on Postgres 16

• test_pageserver_compaction_smoke: release-arm64
• test_timeline_archival_chaos: release-arm64

Failures on Postgres 15

• test_pageserver_compaction_smoke: release-arm64

Failures on Postgres 14

• test_pageserver_compaction_smoke: release-arm64
• test_tx_abort_with_many_relations: release-arm64

# Run all failed tests locally:
scripts/pytest -vv -n $(nproc) -k "test_pageserver_compaction_smoke[release-pg14] or test_tx_abort_with_many_relations[release-pg14] or test_pageserver_compaction_smoke[release-pg15] or test_pageserver_compaction_smoke[release-pg16] or test_timeline_archival_chaos[release-pg16] or test_tx_abort_with_many_relations[release-pg17]"

Test coverage report is not available

_{The comment gets automatically updated with the latest test results
d94a349 at 2024-11-14T20:15:42.331Z :recycle:}

[bayandin]

Added run-benchmarks label, to run benchmarks on next commit