Increase test coverage and refactor parseParameters to ParseParams struct

[ullbergm]

This pull request increases test coverage across the repository and refactors command-line parsing for easier testing.

Key changes:

• Refactor parseParameters to return a ParseParams struct instead of a long tuple, making the code more maintainable and test-friendly.
• Add unit tests for parse flags and environment fallbacks, including leader election parsing.
• Add tests for buildManagerOptions, newLeaseWatcher, and other controller helper functions.
• Improve various tests across pkg/controllers, pkg/util to raise coverage.

Notes:

• Backwards incompatible changes are limited to internal function signatures; top-level main continues to use parseLeaderElectionConfig to validate leader election.
• All tests pass locally and make test completed successfully.

[codecov]

Codecov Report

❌ Patch coverage is 43.29897% with 55 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
cmd/main.go	43.29%	53 Missing and 2 partials ⚠️

📢 Thoughts on this report? Let us know!

[github-actions]

Pull Request closed and locked due to lack of activity.
If you'd like to build on this closed PR, you can clone it using this method: https://stackoverflow.com/a/14969986
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