[ctxprof][nfc] Remove redundant SANITIZER_NO_THREAD_SAFETY_ANALYSIS (#133784)

With the refactoring in PR #133744, `__llvm_ctx_profile_start_context` doesn't need to be marked `SANITIZER_NO_THREAD_SAFETY_ANALYSIS` because `tryStartContextGivenRoot` (where the bulk of the logic went) is.

Author: mtrofin

compiler-rt/lib/ctx_profile/CtxInstrProfiling.cpp

@@ -385,9 +385,9 @@ ContextNode *__llvm_ctx_profile_get_context(FunctionData *Data, void *Callee,
   return Ret;
 }
 
-ContextNode *__llvm_ctx_profile_start_context(
-    FunctionData *FData, GUID Guid, uint32_t Counters,
-    uint32_t Callsites) SANITIZER_NO_THREAD_SAFETY_ANALYSIS {
+ContextNode *__llvm_ctx_profile_start_context(FunctionData *FData, GUID Guid,
+                                              uint32_t Counters,
+                                              uint32_t Callsites) {
   return tryStartContextGivenRoot(FData->getOrAllocateContextRoot(), Guid,
                                   Counters, Callsites);
 }