Fix camera removal detection after toggling monitoring on Linux

Author: shiena

modules/camera/camera_linux.cpp

@@ -169,6 +169,7 @@ inline void CameraLinux::set_monitoring_feeds(bool p_monitoring_feeds) {
 
 	CameraServer::set_monitoring_feeds(p_monitoring_feeds);
 	if (p_monitoring_feeds) {
+		exit_flag.clear();
 		camera_thread.start(CameraLinux::camera_thread_func, this);
 	} else {
 		exit_flag.set();