chore(proxy): pre-load native tls certificates and propagate compute client config

[conradludgate]

Now that we construct the TLS client config for cancellation as well as connect, it feels appropriate to construct the same config once and re-use it elsewhere. It might also help should #7500 require any extra setup, so we can easily add it to all the appropriate call sites.

[github-actions]

7095 tests run: 6796 passed, 0 failed, 299 skipped (full report)

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Flaky tests (3)

Postgres 17

• test_pageserver_gc_compaction_smoke: release-x86-64

Postgres 16

• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64

Postgres 14

• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64

Code coverage* (full report)

• functions: 31.3% (8399 of 26831 functions)
• lines: 48.0% (66657 of 138938 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
ad091c6 at 2024-12-18T17:10:02.135Z :recycle:}