Revert protocol version upgrade

[VladLazar]

Problem

"John pointed out that the switch to protocol version 2 made test_gc_aggressive test flaky: #7692.
I tracked it down, and that is indeed an issue. Conditions for hitting the issue:
The problem occurs in the primary
GC horizon is set to a very low value, e.g. 0.
If the primary is actively writing WAL, and GC runs in the pageserver at the same time that the primary sends a GetPage request, it's possible that the GC advances the GC horizon past the GetPage request's LSN. I'm working on a fix here: #7708." - Heikki

Summary of changes

Use protocol version 1 as default.

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

[hlinnaka]

Please include the explanation of why we're reverting in the commit message too. (If you use github's squash & merge, it will be copied from the PR description by default I think)

[VladLazar]

If you use github's squash & merge, it will be copied from the PR description by default I think

Yep. That's what I usually do. Thanks for the heads-up.

[github-actions]

3060 tests run: 2927 passed, 0 failed, 133 skipped (full report)

---

Flaky tests (1)

Postgres 16

• test_vm_bit_clear_on_heap_lock: debug

Code coverage* (full report)

• functions: 31.4% (6330 of 20161 functions)
• lines: 47.3% (47753 of 100970 lines)

* collected from Rust tests only

---

_{The comment gets automatically updated with the latest test results
93bff7e at 2024-05-13T11:04:43.457Z :recycle:}