test: stabilize memoize weak-ref GC spec on nvim v0.11.4

[Copilot]

Summary

This PR addresses the failing GitHub Actions job tests (ubuntu-latest, v0.11.4) caused by a flaky weak-reference GC assertion in memoize_spec.lua. The test now isolates memoize behavior from parser/tree lifetime variance and tolerates delayed collection on v0.11.4.

Related Issues

Related #

Changes

• Isolate parser/tree references in the weak-ref fixture
  • Clear both parser and parsed root before releasing the file reference.
• Stabilize GC-sensitive assertion
  • Replace single-pass GC with bounded repeated collection (up to 10 rounds) before asserting weak ref release.
• Scope
  • Test-only change in tests/plenary/utils/memoize_spec.lua; no runtime behavior changes.

file.parser = nil
file.root = nil

for _ = 1, 10 do
  if weak.file == nil then
    break
  end
  collect()
end

Checklist

I confirm that I have:

• Followed the
  Conventional Commits
  specification (e.g., feat: add new feature, fix: correct bug,
  docs: update documentation).
• My PR title also follows the conventional commits specification.
• Updated relevant documentation, if necessary.
• Thoroughly tested my changes.
• Added tests (if applicable) and verified existing tests pass with
  make test.
• Checked for breaking changes and documented them, if any.