fix(adapter): password not set in role drop

[myrrc]

Problem

When entry was dropped and password wasn't set, new entry
had uninitialized memory in controlplane adapter

Resolves: https://github.com/neondatabase/cloud/issues/14914

Summary of changes

Initialize password in all cases, add tests.
Minor formatting for less indentation

[github-actions]

7095 tests run: 6798 passed, 0 failed, 297 skipped (full report)

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Flaky tests (8)

Postgres 17

• test_tenant_config: debug-x86-64

Postgres 16

• test_pgdata_import_smoke[8-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64
• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64

Postgres 15

• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64
• test_pgdata_import_smoke[8-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64
• test_parallel_copy: release-arm64
• test_physical_replication_config_mismatch_too_many_known_xids: release-arm64

Postgres 14

• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64

Code coverage* (full report)

• functions: 31.4% (8401 of 26778 functions)
• lines: 48.1% (66630 of 138651 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
d1c5eb0 at 2024-12-13T22:28:05.605Z :recycle:}

[myrrc]

Regarding failures of test_pageserver_small_inmemory_layers, I fail to reproduce the error, though I notice the test may run for 1:50 or so