Remove unreachable break after LOG(FATAL) in LogOnce.cpp (#59520)

Summary:
Pull Request resolved: #59520

Clang reports `-Wunreachable-code-break` here: the `break` follows `LOG(FATAL)`, which never returns, so control can never reach the `break`. Removing it silences the warning and does not change behavior. It ends the last label of the switch, so it is redundant anyway.

Changelog: [Internal]

Reviewed By: dtolnay

Differential Revision: D126709681

Author: r-barnes

packages/react-native/ReactCxxPlatform/react/logging/LogOnce.cpp

@@ -34,7 +34,6 @@ LogOnceWrapper::~LogOnceWrapper() {
     case Severity::Fatal:
     default:
       LOG(FATAL) << message;
-      break;
   }
 
   loggedMessages.insert(message);