refactor(agent): improve drupal hook map error logging

[bduranleau-nr]

Addresses #1099
Enhances #1100

[newrelic-php-agent-bot]

Test Suite	Status	Result
Multiverse	✅	16/16 passing
SOAK	✅	85/85 passing

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 78.12%. Comparing base (f58a459) to head (b3531f5).

Files with missing lines	Patch %	Lines
agent/fw_drupal8.c	75.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1101      +/-   ##
==========================================
- Coverage   78.13%   78.12%   -0.02%     
==========================================
  Files         193      193              
  Lines       27976    27979       +3     
==========================================
- Hits        21859    21858       -1     
- Misses       6117     6121       +4     

Flag	Coverage Δ
agent-for-php-7.2	78.37% <0.00%> (-0.01%)	⬇️
agent-for-php-7.3	78.38% <0.00%> (-0.01%)	⬇️
agent-for-php-7.4	78.24% <90.00%> (-0.01%)	⬇️
agent-for-php-8.0	77.45% <90.00%> (-0.01%)	⬇️
agent-for-php-8.1	77.76% <90.00%> (-0.01%)	⬇️
agent-for-php-8.2	77.38% <90.00%> (-0.01%)	⬇️
agent-for-php-8.3	77.38% <90.00%> (-0.01%)	⬇️
agent-for-php-8.4	77.40% <90.00%> (-0.01%)	⬇️

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