chore(spanner): add missing project_id label to metrics

[olavloite]

Adds the missing project_id label to metrics.

Note: Added as a 'chore:' and not 'fix:' as these metrics had not yet been released.

[gemini-code-assist]

Code Review

This pull request adds the project_id attribute to the monitored resource labels in resource_to_monitored_resource and updates the corresponding unit and mock tests to assert its presence. Feedback suggests refactoring the match block in exporter.rs to reuse the existing is_monitored_resource_label helper function, which reduces duplication and improves maintainability.

[gemini-code-assist]

Instead of duplicating the list of monitored resource labels here, we can reuse the existing helper function is_monitored_resource_label which is already defined in this file. This reduces duplication and prevents future inconsistencies.

        if is_monitored_resource_label(key_str) {
            labels.insert(key_str.to_string(), value_to_string(val));
        }

[alvarowolfx]

this makes a lot of sense to me. Any reason not to reason the method @olavloite ?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.91%. Comparing base (2faf555) to head (b8ff358).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6843      +/-   ##
==========================================
- Coverage   96.92%   96.91%   -0.01%     
==========================================
  Files         327      327              
  Lines      108648   108651       +3     
==========================================
- Hits       105309   105302       -7     
- Misses       3339     3349      +10     

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[alvarowolfx]

gonna approve it, but ideally it should be refactored to use is_monitored_resource_label. Also you can use impl instead of chore, since you don't consider this a fix and metrics is still not available.