[Sanitizer][Darwin] Mark test UNSUPPORTED instead of XFAIL

This is test is failing/passing depending on the host OS version.  Need
to investigate/fix before re-enabling.

rdar://95982696

compiler-rt/test/sanitizer_common/TestCases/symbolize_stack.cpp

@@ -3,7 +3,7 @@
 // Test that symbolizer does not crash on frame with large function name.
 
 // On Darwin LSan reports a false positive
-// XFAIL: darwin && lsan
+// UNSUPPORTED: darwin && lsan
 
 #include <sanitizer/common_interface_defs.h>
 #include <vector>