Extract shared Jira-DC stability helpers for integration tests

[lipkau]

Why

Server/DC integration stability fixes were implemented in-line in integration tests during incident response. Keeping this logic duplicated across test files increases maintenance cost and makes regressions more likely.

Problem

Retry/fallback and fixture-anchoring behavior for known Jira DC instability patterns are currently test-file local rather than shared.

Impact

• Harder to maintain consistency across integration suites
• Higher chance of reintroducing flaky patterns in future tests

Suggested approach

1. Extract reusable helpers into Tests/Helpers/IntegrationTestTools.ps1.
2. Centralize patterns for:
   • bounded retry for transient version-delete 405
   • safe fallback to removeAndSwap in integration orchestration
   • fixture-anchored query builders for DC-sensitive JQL paths
3. Update affected test files to consume shared helpers.

Related areas

• Tests/Integration/Versions.Integration.Tests.ps1
• Tests/Integration/Search.Integration.Tests.ps1
• Tests/Helpers/IntegrationTestTools.ps1