[MM-1915] Add Deactivate Account - server side (#8699)

config/default.json

@@ -71,6 +71,7 @@
         "EnableTeamCreation": true,
         "EnableUserCreation": true,
         "EnableOpenServer": false,
+        "EnableUserDeactivation": false,
         "RestrictCreationToDomains": "",
         "EnableCustomBrand": false,
         "CustomBrandText": "",