fix(pageserver): make wal connstr a connstr

[skyzh]

Problem

The list timeline API gives something like "wal_source_connstr":"PgConnectionConfig { host: Domain(\"safekeeper-5.us-east-2.aws.neon.build\"), port: 6500, password: Some(REDACTED-STRING) }", which is weird. This pull request makes it somehow like a connection string. This field is not used at least in the neon database, so I assume no one is reading or parsing it.

Summary of changes

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

[koivunej]

Many parts of timeline detail are/is/exists just for debugging. I cannot see how this could hurt, the named debug output certainly was not useful.

[github-actions]

3108 tests run: 2982 passed, 0 failed, 126 skipped (full report)

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Flaky tests (2)

Postgres 16

• test_timeline_deletion_with_files_stuck_in_upload_queue: debug

Postgres 14

• test_pageserver_init_node_id: debug

Code coverage* (full report)

• functions: 31.4% (6446 of 20499 functions)
• lines: 48.3% (49791 of 103171 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
03342c8 at 2024-05-22T19:15:02.132Z :recycle:}