[#14044] Strengthen coroutine lifecycle regression

[cj848]

Why

Follow-up to #14046. The original unit test verifies the block-aware callback contract, but reverting the production change fails at the interface assertion before exercising the stale-current-trace behavior.

This revision keeps both callback contracts executable in the test and models the lifecycle observed around coroutine/Reactor nesting: before() starts trace A, a simulated nested callback clears the async context's current trace, and after() must still close the exact block from trace A.

Related to #14044.

What

• Simulate the current async trace being cleared between ResumeWithInterceptor.before() and after().
• Exercise either the pre-fix AroundInterceptor or fixed BlockAroundInterceptor callback contract from the same test source.
• Verify no second currentAsyncTraceObject() lookup and preserve exact block identity plus enter/begin/leave/close ordering.

Regression proof

• Pre-fix superclass: ResumeWithInterceptorTest fails because AsyncContextSpanEventSimpleAroundInterceptor.after() calls currentAsyncTraceObject() after it has been cleared.
• Block-aware superclass: the same test passes and closes the block returned by before().

Verification

• ./mvnw -q -pl agent-module/plugins/kotlin-coroutines -am -DskipITs -Dtest=ResumeWithInterceptorTest -Dsurefire.failIfNoSpecifiedTests=false test
• ./mvnw -q -pl agent-module/plugins/kotlin-coroutines -am -DskipITs test
• Coroutines_1_6_IT: 38 tests, 0 failures/errors/skips
• git diff --check

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[cj848]

Closing this follow-up to keep the upstream change represented by the already merged #14046. The behavioral test refinement will not be proposed as a separate PR.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud