Reduce some G-code strings

Marlin/src/lcd/menu/menu_ubl.cpp

@@ -139,8 +139,8 @@ void _lcd_ubl_custom_mesh() {
  * UBL Adjust Mesh Height Command
  */
 void _lcd_ubl_adjust_height_cmd() {
-  char ubl_lcd_gcode[16];
-  const int ind = ubl_height_amount > 0 ? 9 : 10;
+  char ubl_lcd_gcode[13];
+  const int ind = ubl_height_amount > 0 ? 6 : 7;
   strcpy_P(ubl_lcd_gcode, PSTR("G29P6C-"));
   sprintf_P(&ubl_lcd_gcode[ind], PSTR(".%i"), ABS(ubl_height_amount));
   queue.inject(ubl_lcd_gcode);
@@ -187,7 +187,7 @@ void _lcd_ubl_edit_mesh() {
    * UBL Validate Custom Mesh Command
    */
   void _lcd_ubl_validate_custom_mesh() {
-    char ubl_lcd_gcode[24];
+    char ubl_lcd_gcode[20];
     sprintf_P(ubl_lcd_gcode, PSTR("G28\nG26CPH%" PRIi16 TERN_(HAS_HEATED_BED, "B%" PRIi16))
       , custom_hotend_temp
       #if HAS_HEATED_BED