fix(agent): fix memleak in Laravel Queue instrumentation

[zsistla]

Free strings that were strdup-ed but not being freed.

[newrelic-php-agent-bot]

Test Suite	Status	Result
Multiverse	✅	8/8 passing
SOAK	✅	72/72 passing

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 78.00%. Comparing base (94a41f5) to head (acf90cb).

Files with missing lines	Patch %	Lines
agent/fw_laravel_queue.c	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1014      +/-   ##
==========================================
- Coverage   78.02%   78.00%   -0.02%     
==========================================
  Files         197      197              
  Lines       27418    27424       +6     
==========================================
  Hits        21392    21392              
- Misses       6026     6032       +6     

Flag	Coverage Δ
agent-for-php-7.2	78.15% <0.00%> (-0.01%)	⬇️
agent-for-php-7.3	78.17% <0.00%> (-0.01%)	⬇️
agent-for-php-7.4	77.88% <0.00%> (-0.01%)	⬇️
agent-for-php-8.0	77.24% <0.00%> (-0.02%)	⬇️
agent-for-php-8.1	?
agent-for-php-8.2	77.35% <0.00%> (-0.02%)	⬇️
agent-for-php-8.3	77.35% <0.00%> (-0.02%)	⬇️
agent-for-php-8.4	77.37% <0.00%> (-0.02%)	⬇️

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