feat(pageserver): dump read path on missing key error

[skyzh]

Problem

helps investigate #10482

Summary of changes

In debug mode and testing mode, we will record all files visited by a read operation, and print it out when it errors.

[github-actions]

7425 tests run: 7073 passed, 0 failed, 352 skipped (full report)

---

Flaky tests (3)

Postgres 17

• test_pageserver_gc_compaction_idempotent[after_restart]: release-arm64-without-lfc
• test_nbtree_pagesplit_cycleid: debug-x86-64-without-lfc

Postgres 14

• test_scrubber_physical_gc_ancestors[2]: release-arm64-with-lfc

Code coverage* (full report)

• functions: 33.3% (8592 of 25829 functions)
• lines: 49.1% (72335 of 147322 lines)

* collected from Rust tests only

---

_{The comment gets automatically updated with the latest test results
171663c at 2025-02-06T21:48:19.288Z :recycle:}

[skyzh]

#10482 is already resolved in #10543 but I think this patch might be helpful for any future read errors we might encounter on the read path.