Return Past instead of Present or Future when commit_lsn < min_lsn

[arpad-m]

Implements an approach different from the one #7488 chose: We now return past instead of present (orfuture) when encountering the edge case where commit_lsn < min_lsn. In my opinion, both past and present are correct responses, but past is slightly better as the lsn returned by present with #7488 is one too "new". In practice, this shouldn't matter much, but shrug.

We agreed in slack that this is the better approach: https://neondb.slack.com/archives/C03F5SM1N02/p1713871064147029

[koivunej]

Looking good.

Additionally I would like if we could move/add some of the documentation about this API and it's intention to endpoint to the openapi.yml. At least that's where I started when looking understanding how should this api work. Could be I missed some inter-doc link, if this is there already.

[github-actions]

2796 tests run: 2675 passed, 0 failed, 121 skipped (full report)

---

Flaky tests (1)

Postgres 15

• test_partial_evict_tenant[relative_spare]: release

Code coverage* (full report)

• functions: 28.3% (6546 of 23138 functions)
• lines: 47.0% (46234 of 98432 lines)

* collected from Rust tests only

---

_{The comment gets automatically updated with the latest test results
bc995db at 2024-04-26T14:18:11.151Z :recycle:}