[SM-1031] Remove SecretsManager & showDDG compile flags (#8610)

Remove old compile flags which should no longer be required, and may even cause issues. secretsManager: false hides the app switcher which is now used for more than just secrets manager.

apps/desktop/config/development.json

@@ -1,7 +1,6 @@
 {
   "devFlags": {},
   "flags": {
-    "showDDGSetting": true,
     "enableCipherKeyEncryption": false
   }
 }

apps/desktop/config/production.json

@@ -1,6 +1,5 @@
 {
   "flags": {
-    "showDDGSetting": true,
     "enableCipherKeyEncryption": false
   }
 }