fix(agent): fix potential memleak when calling newrelic_end_transaction(true)

[ZNeumann]

Some transaction globals were leaked when calling newrelic_end_transaction(true). The freeing of these transaction globals has been moved to join all the other transaction globals to alleviate this.

In so doing, additional rshutdown methods are needed. This is because the transaction globals contain reference incremented zvals. If we wait until postdeactivate, those zvals will be in an undefined state and the data structures containing those references cannot be properly freed. In line with other transaction globals, we trigger a shutdown method during rshutdown to free these globals while the zvals are still valid.

[newrelic-php-agent-bot]

Test Suite	Status	Result
Multiverse	❌	15/16 passing
SOAK	❌	83/85 passing

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.15%. Comparing base (469e63e) to head (d90b538).
⚠️ Report is 5 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1072      +/-   ##
==========================================
+ Coverage   78.13%   78.15%   +0.01%     
==========================================
  Files         193      193              
  Lines       28045    28053       +8     
==========================================
+ Hits        21914    21925      +11     
+ Misses       6131     6128       -3     

Flag	Coverage Δ
agent-for-php-7.2	78.40% <100.00%> (+0.01%)	⬆️
agent-for-php-7.3	78.42% <100.00%> (+0.01%)	⬆️
agent-for-php-7.4	78.28% <100.00%> (+0.01%)	⬆️
agent-for-php-8.0	77.48% <100.00%> (+0.01%)	⬆️
agent-for-php-8.1	77.79% <100.00%> (+0.01%)	⬆️
agent-for-php-8.2	77.41% <100.00%> (+0.01%)	⬆️
agent-for-php-8.3	77.41% <100.00%> (+0.01%)	⬆️
agent-for-php-8.4	77.43% <100.00%> (+0.01%)	⬆️

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