Update platform tests to use '.test' folder

buildroot/share/tests/megaatmega2560_tests

@@ -3,15 +3,13 @@
 # exit on first failure
 set -e
 
-#
-# Backup pins_RAMPS.h
-#
-cp Marlin/src/pins/pins_RAMPS.h Marlin/src/pins/pins_RAMPS.h.backup
+env_backup
+
 #
 # Build with the default configurations
 #
-restore_configs
 exec_test $1 $2 "Default Configuration"
+
 #
 # Test 2 extruders (one MAX6675) and heated bed on basic RAMPS 1.4
 # Test a "Fix Mounted" Probe with Safe Homing, some arc options,
@@ -311,5 +309,4 @@ exec_test $1 $2 "TMC2208 Config"
 #
 #
 
-#clean up
-restore_configs
+env_restore