ACMS-3508: Using null coalescing operator to manage the logic.

Author: apathak18

settings/config.settings.php

@@ -23,8 +23,8 @@
  * settings.php, and we will not overwrite it.
  */
 // phpcs:ignore
-$drs_override_config_directories = !isset($drs_override_config_directories) ? TRUE : FALSE;
-$drs_override_site_studio_sync_directories = !isset($drs_override_site_studio_sync_directories) ? TRUE : FALSE;
+$drs_override_config_directories = $drs_override_config_directories ?? FALSE;
+$drs_override_site_studio_sync_directories = $drs_override_site_studio_sync_directories ?? FALSE;
 
 /**
  * Site path.