Add Supportability metrics for partial granularity tracing

[hmstepanek]

Overview

Add the following Supportability metrics:

• Supportability/DistributedTrace/PartialGranularity/<partial granularity type>/Span/Instrumented - The total number of span events that were instrumented and would have been recorded (if the trace was full granularity) before partial granularity dropped them.
• Supportability/DistributedTrace/PartialGranularity/<partial granularity type>/Span/Kept - The total number of span events that were recorded and kept by partial granularity (aka that were not dropped).
• Supportability/<language>/PartialGranularity/<type> - This MUST be sent when partial granularity is enabled. The pipeline will add a tag to the entity when this metric is sent so the DT UI can indicate partial granularity tracing is on.

[github-actions]

❌MegaLinter analysis: Error

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	7		0	0	0.92s
✅ MARKDOWN	markdownlint	7	0	0	0	1.19s
❌ PYTHON	ruff	948	0	1	0	1.07s
✅ PYTHON	ruff-format	948	3	0	0	0.36s
✅ YAML	prettier	15	0	0	0	1.56s
✅ YAML	v8r	15		0	0	5.69s
✅ YAML	yamllint	15		0	0	0.7s

Detailed Issues

❌ PYTHON / ruff - 1 error

::error title=Ruff (F821),file=newrelic/core/application.py,line=1377,col=103,endLine=1377,endColumn=120::newrelic/core/application.py:1377:103: F821 Undefined name `partial_gran_type`

See detailed reports in MegaLinter artifacts

[codecov-commenter]

Codecov Report

❌ Patch coverage is 89.21569% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.81%. Comparing base (59633ac) to head (2e077c6).
⚠️ Report is 3 commits behind head on develop-hybrid-core-tracing.

Files with missing lines	Patch %	Lines
newrelic/config.py	51.72%	14 Missing ⚠️
newrelic/core/node_mixin.py	94.91%	1 Missing and 2 partials ⚠️
newrelic/core/agent.py	50.00%	2 Missing ⚠️
newrelic/core/data_collector.py	71.42%	1 Missing and 1 partial ⚠️
newrelic/api/transaction.py	98.27%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                       Coverage Diff                       @@
##           develop-hybrid-core-tracing    #1560      +/-   ##
===============================================================
+ Coverage                        81.76%   81.81%   +0.05%     
===============================================================
  Files                              207      207              
  Lines                            23943    24081     +138     
  Branches                          3796     3820      +24     
===============================================================
+ Hits                             19576    19702     +126     
- Misses                            3101     3105       +4     
- Partials                          1266     1274       +8     

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