Initial tests for git module refactoring

[ogenstad]

Why

Adds tests to capture current state and highlight things that needs to be refactored

What changed

• Add tests for git push failures which currently show an undesired behaviour

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Summary by cubic

Add Gogs-backed integration tests that pin current infrahub.git behavior across push rejections, merge failures, read-only updates, repo setup errors, and sync conflicts; push still returns True on rejection and remotes don’t advance (INFP-546 T005–T010).

^{Written for commit fc73474. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

<sub>Shadow auto-approve: would auto-approve. This pull request only adds integration tests for git push failure scenarios and updates a documentation task list, with no changes to source code, configuration, or any production-critical logic.

Re-trigger cubic</sub>

[codspeed-hq]

Merging this PR will not alter performance

✅ 12 untouched benchmarks

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_{Comparing pog-infp-546-tests (fc73474) with develop (248c0d1)}

[cubic-dev-ai]

0 issues found across 5 files (changes from recent commits).

<sub>Shadow auto-approve: would auto-approve. These changes add integration tests and update a task tracking document, with no modifications to production code, infrastructure, or critical logic, so the risk of breakage is extremely low.

Re-trigger cubic</sub>