pageserver: make vectored get the default read path for the pageserver

[VladLazar]

Problem

Vectored get is already enabled in all prod regions without validation. The pageserver defaults are out of sync however.

Summary of changes

Update the pageserver defaults to match the prod config. Also means that when running tests locally, people don't have to use the env vars to get the prod config.

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

[github-actions[bot]]

3132 tests run: 3011 passed, 0 failed, 121 skipped (full report)

---

Code coverage* (full report)

• functions: 32.9% (7009 of 21310 functions)
• lines: 50.1% (55742 of 111313 lines)

* collected from Rust tests only

---

_{The comment gets automatically updated with the latest test results
16e4024b3cce18a3244a68d894f71d3db8b0191c at 2024-07-26T11:45:03.675Z :recycle:}

[arpad-m]

The PR seems to have merge conflicts.