fix[rule]: update check for time machine encryption

changing to CIS method

Issue #538

rules/system_settings/system_settings_time_machine_encrypted_configure.yaml

@@ -3,15 +3,7 @@ title: Ensure Time Machine Volumes are Encrypted
 discussion: |
   Time Machine volumes _MUST_ be encrypted.
 check: |
-  error_count=0
-  for tm in $(/usr/bin/tmutil destinationinfo 2>/dev/null| /usr/bin/awk -F': ' '/Name/{print $2}'); do
-    tmMounted=$(/usr/sbin/diskutil info "${tm}" 2>/dev/null | /usr/bin/awk '/Mounted/{print $2}')
-    tmEncrypted=$(/usr/sbin/diskutil info "${tm}" 2>/dev/null | /usr/bin/awk '/FileVault/{print $2}')
-    if [[ "$tmMounted" = "Yes" && "$tmEncrypted" = "No" ]]; then
-        ((error_count++))
-    fi
-  done
-  echo "$error_count"
+  /usr/bin/sudo /usr/bin/defaults read /Library/Preferences/com.apple.TimeMachine.plist | grep -c NotEncrypted
 result:
   integer: 0
 fix: |