pageserver: remove legacy attach/detach APIs from swagger

[jcsp]

Problem

Since the location config API was added, the attach and detach endpoints are deprecated. Hiding them from consumers of the swagger definition is a precursor to removing them

Neon's cloud no longer uses this api since https://github.com/neondatabase/cloud/pull/10538

Fully removing the APIs will implicitly make use of generation numbers mandatory, and should happen alongside #5388, which will happen once we're happy that the storage controller is ready for prime time.

Summary of changes

• Remove /attach and /detach from pageserver's swagger file

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

[problame]

The (undocumented) procedure for removals is to do that in the cloud.git first. Did that happen already?

[github-actions]

2418 tests run: 2298 passed, 0 failed, 120 skipped (full report)

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Flaky tests (5)

Postgres 16

• test_remote_timeline_client_calls_started_metric: debug
• test_vm_bit_clear_on_heap_lock: release

Postgres 15

• test_pg_regress[None]: debug
• test_timeline_deletion_with_files_stuck_in_upload_queue: debug

Postgres 14

• test_timeline_deletion_with_files_stuck_in_upload_queue: debug

Code coverage* (full report)

• functions: 28.8% (6778 of 23531 functions)
• lines: 47.6% (41240 of 86559 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
c0ffd8e at 2024-02-23T16:38:48.634Z :recycle:}

[jcsp]

The (undocumented) procedure for removals is to do that in the cloud.git first. Did that happen already?

In this case I've just announced the change to that team (I had earlier checked that on the linked PR they weren't using the API any more).