TEMP_WATCH_PERIOD adjustment

Increased temperature watch period from 20 to 40 seconds

Marlin/Configuration_adv.h

@@ -74,7 +74,7 @@
    * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
    * WATCH_TEMP_INCREASE should not be below 2.
    */
-  #define WATCH_TEMP_PERIOD 20                // Seconds
+  #define WATCH_TEMP_PERIOD 40                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
 #endif