ContendedCallTraceStorageTest: skip on musl+aarch64 debug (CTimer::unregisterThread race)

[jbachorik]

Summary

ContendedCallTraceStorageTest is disabled on musl+aarch64 debug via isPlatformSupported() returning false because CTimer::unregisterThread races with concurrent thread teardown on that combination, causing spurious failures.

Affected file

ddprof-test/src/test/java/com/datadoghq/profiler/ContendedCallTraceStorageTest.java

Reproduction

Run the test with:

• libc: musl
• arch: aarch64
• build type: debug

The race manifests as a crash or hang inside CTimer::unregisterThread during test teardown when profiled threads exit concurrently.

Investigation notes

• The bug is pre-existing and unrelated to the StringDictionary refactor in PR fix(profiler): lock-free class/endpoint/context maps via StringDictionary #524.
• CTimer relies on signal delivery to the thread being unregistered; on musl+aarch64 debug the timing of thread teardown vs. signal delivery is different enough to expose a race.
• A proper fix likely requires guarding unregisterThread with the same lock as registerThread, or making the unregister step signal-delivery-free.

Tracked by

PR #524 added the skip; this issue tracks the underlying bug.