Final tweaks to M111 output

Marlin/Marlin_main.cpp

     uint8_t comma = 0;
     for (uint8_t i = 0; i < COUNT(debug_strings); i++) {
       if (TEST(marlin_debug_flags, i)) {
-        if (comma++) SERIAL_CHAR('|');
+        if (comma++) SERIAL_CHAR(',');
         serialprintPGM((char*)pgm_read_word(&(debug_strings[i])));
       }
     }

Marlin/language.h

 #define MSG_T_MINTEMP                       "MINTEMP triggered"
 
 // Debug
-#define MSG_DEBUG_PREFIX                    "DEBUG: "
+#define MSG_DEBUG_PREFIX                    "DEBUG:"
 #define MSG_DEBUG_OFF                       "off"
 #define MSG_DEBUG_ECHO                      "ECHO"
 #define MSG_DEBUG_INFO                      "INFO"