storage controller: handle legacy TenantConf in consistency_check

[jcsp]

Problem

We were comparing serialized configs from the database with serialized configs from memory. If fields have been added/removed to TenantConfig, this generates spurious consistency errors. This is fine in test environments, but limits the usefulness of this debug API in the field.

Closes: #10369

Summary of changes

• Do a decode/encode cycle on the config before comparing it, so that it will have exactly the expected fields.

[github-actions]

7326 tests run: 6949 passed, 0 failed, 377 skipped (full report)

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Flaky tests (4)

Postgres 17

• test_compute_pageserver_connection_stress: release-x86-64
• test_physical_replication_config_mismatch_max_locks_per_transaction: release-arm64
• test_scrubber_tenant_snapshot[4]: debug-x86-64
• test_s3_wal_replay: release-x86-64

Code coverage* (full report)

• functions: 33.7% (8423 of 25018 functions)
• lines: 49.2% (70459 of 143318 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
2118484 at 2025-01-16T11:10:45.502Z :recycle:}