{event,output}/Thread: downgrade realtime scheduling errors to "info"

These messages can be confusing, but they are not critical.

src/event/Thread.cxx

@@ -57,7 +57,7 @@ EventThread::Run() noexcept
 		try {
 			SetThreadRealtime();
 		} catch (...) {
-			LogError(std::current_exception(),
+			Log(LogLevel::INFO, std::current_exception(),
 			    "RTIOThread could not get realtime scheduling, continuing anyway");
 		}
 	}

src/output/Thread.cxx

@@ -406,7 +406,7 @@ AudioOutputControl::Task() noexcept
 	try {
 		SetThreadRealtime();
 	} catch (...) {
-		LogError(std::current_exception(),
+		Log(LogLevel::INFO, std::current_exception(),
 		    "OutputThread could not get realtime scheduling, continuing anyway");
 	}