Isolate more the mfa service (#16925)

* Isolate more the mfa service

* Simplifing the mfa service

* Removing channels and adding waitgroup

* Migrating mfa service to regular errors

* Fixing tests

* i18n extract

* Addressing PR review comments

* Removing unneeded struct

i18n/en.json

@@ -6935,33 +6935,21 @@
     "translation": "Mattermost Security Bulletin"
   },
   {
-    "id": "mfa.activate.authenticate.app_error",
-    "translation": "Error attempting to authenticate MFA token."
+    "id": "mfa.activate.app_error",
+    "translation": "Unable to update MFA active status for the user."
   },
   {
     "id": "mfa.activate.bad_token.app_error",
     "translation": "Invalid MFA token."
   },
   {
-    "id": "mfa.activate.save_active.app_error",
+    "id": "mfa.deactivate.app_error",
     "translation": "Unable to update MFA active status for the user."
   },
-  {
-    "id": "mfa.deactivate.save_active.app_error",
-    "translation": "Unable to update MFA active status for the user."
-  },
-  {
-    "id": "mfa.deactivate.save_secret.app_error",
-    "translation": "Error clearing the MFA secret."
-  },
   {
     "id": "mfa.generate_qr_code.create_code.app_error",
     "translation": "Error generating QR code."
   },
-  {
-    "id": "mfa.generate_qr_code.save_secret.app_error",
-    "translation": "Error saving the MFA secret."
-  },
   {
     "id": "mfa.mfa_disabled.app_error",
     "translation": "Multi-factor authentication has been disabled on this server."