[CLIENT-2159] Fix reference count leaks when a user passes in a MetricsPolicy to client.enable_metrics()

[DomPeliniAerospike]

Decrementing reference for dangling pointers in metrics_policy intialization

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.00%. Comparing base (f762c03) to head (b6118c1).
⚠️ Report is 7 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #818      +/-   ##
==========================================
- Coverage   82.03%   82.00%   -0.03%     
==========================================
  Files          99       99              
  Lines       14724    13912     -812     
==========================================
- Hits        12079    11409     -670     
+ Misses       2645     2503     -142     

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[juliannguyen4]

Hey Dominic, just one issue I found. Otherwise LGTM

[juliannguyen4]

Suggested change

Py_DECREF(py_report_dir);

This may cause a memory error later when we try to read the string pointed to by report_dir, because the string is wrapped around the py_report_dir object. If py_report_dir gets garbage collected, then the string would become invalid:

https://docs.python.org/3/c-api/unicode.html#c.PyUnicode_AsUTF8AndSize
https://docs.python.org/3/c-api/unicode.html#c.PyUnicode_AsUTF8

So you would need to move this Py_DECREF to after the last time we read from report_dir, which is the line with strcpy