tests(agent): Removes Monolog library tests

[mfulb]

The Monolog library tests have been moved to the multiverse tests.
This PR removes the test from the integration tests.
The PR also adds a test for the Monolog detection/state metrics to be consistent with other logging libraries tested in the integration tests.

[newrelic-php-agent-bot]

Test Suite	Status	Result
Multiverse	✅	8/8 passing
SOAK	✅	79/79 passing

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.22%. Comparing base (c8a539a) to head (25f2b97).

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1040      +/-   ##
==========================================
- Coverage   77.87%   77.22%   -0.66%     
==========================================
  Files         198      198              
  Lines       27899    27899              
==========================================
- Hits        21727    21544     -183     
- Misses       6172     6355     +183     

Flag	Coverage Δ
agent-for-php-7.2	77.44% <ø> (-0.69%)	⬇️
agent-for-php-7.3	77.46% <ø> (-0.69%)	⬇️
agent-for-php-7.4	77.18% <ø> (-0.69%)	⬇️
agent-for-php-8.0	76.57% <ø> (-0.69%)	⬇️
agent-for-php-8.1	76.97% <ø> (-0.68%)	⬇️
agent-for-php-8.2	76.58% <ø> (-0.68%)	⬇️
agent-for-php-8.3	76.58% <ø> (-0.68%)	⬇️
agent-for-php-8.4	76.60% <ø> (-0.68%)	⬇️

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