Resolve Micronaut duplicate transactions/lost custom attributes issues

[sharvath-newrelic]

Overview

This PR aims to resolve a couple of issues where custom attributes and transaction names set from a @ServerFilter were being dropped, and requests sometimes produced two Transaction events for one HTTP call. Two areas have been addressed:

• PipeliningServerHandler_Instrumentation (all 5 micronaut-http-server-netty-4.x.0 modules): a change was made to call Weaver.callOriginal() before expiring the request token in channelReadComplete(), not after, as expiring first let a synchronous mid-request dispatch run unlinked, which resulted in a phantom transaction.
• PropagatedContext_Instrumentation (micronaut-core-4.0.0 and 4.3.0): relink the transaction's token across PropagatedContext.wrap(Runnable/Callable), the hop Micronaut uses for @ExecuteOn thread offload. Backed by two small wrapper classes (NRTokenRunnableWrapper, NRTokenCallableWrapper).

Related Github Issue

Resolves #3038 (awaiting potential feedback from user)

Testing

Unit tests have been added (JUnit + Mockito, mockito-inline for static mocking) covering both fixes: token-expiry ordering in the netty handler, and the wrap/relink behavior and its cases in PropagatedContext_Instrumentation and its wrappers.

Passing Micronaut AITs.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.85%. Comparing base (11af35c) to head (64636bf).
⚠️ Report is 45 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3085      +/-   ##
============================================
- Coverage     70.92%   70.85%   -0.07%     
- Complexity    10681    10709      +28     
============================================
  Files           871      873       +2     
  Lines         43006    43135     +129     
  Branches       6503     6526      +23     
============================================
+ Hits          30501    30565      +64     
- Misses         9557     9611      +54     
- Partials       2948     2959      +11     

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