Nightly Benchmarks: use pgbench from artifacts

[bayandin]

We don't use statically linked OpenSSL anymore (#10302),
it's ok to switch to Neon's pgbench for pgvector benchmarks

[Bodobolero]

thanks for taking care

[github-actions]

7414 tests run: 7063 passed, 0 failed, 351 skipped (full report)

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Flaky tests (7)

Postgres 17

• test_pageserver_gc_compaction_idempotent[after_restart]: release-x86-64-with-lfc
• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64-without-lfc, release-arm64-with-lfc, debug-x86-64-without-lfc
• test_pgdata_import_smoke[8-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64-with-lfc, debug-x86-64-without-lfc, release-arm64-without-lfc

Code coverage* (full report)

• functions: 33.4% (8509 of 25499 functions)
• lines: 49.1% (71462 of 145505 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
4ddd681 at 2025-01-30T09:41:41.782Z :recycle:}

[bayandin]

We can merge this PR after the next storage release.
Currently, the latest version of Neon artifacts points to the version with still statically linked OpenSSL and pgbench still fail:

• https://github.com/neondatabase/neon/actions/runs/12751652078

[bayandin]

Running it again: https://github.com/neondatabase/neon/actions/runs/13048547685

UPD: Tests have passed!