storcon: refine chaos selection logic

[jcsp]

Problem

In #10438 it was pointed out that it would be good to avoid picking tenants in ID order, and also to avoid situations where we might double-select the same tenant.

There was an initial swing at this in #10443, where Chi suggested a simpler approach which is done in this PR

Summary of changes

• Split total set of tenants into in and out of home AZ
• Consume out of home AZ first, and if necessary shuffle + consume from out of home AZ

[github-actions]

7414 tests run: 7061 passed, 0 failed, 353 skipped (full report)

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Flaky tests (7)

Postgres 17

• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: debug-x86-64-without-lfc, release-arm64-without-lfc, release-arm64-with-lfc
• test_pgdata_import_smoke[8-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: debug-x86-64-without-lfc, release-arm64-with-lfc, release-arm64-without-lfc
• test_peer_recovery: release-arm64-with-lfc

Code coverage* (full report)

• functions: 33.3% (8514 of 25536 functions)
• lines: 49.1% (71513 of 145560 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
ff63ad0 at 2025-01-30T22:54:14.544Z :recycle:}