Enable custom email parameter at service account creation

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What does this MR do and why?

Enable custom email parameter at service account creation

Currently service accounts are created with an autogenerated email address. This change allows to specify a custom email address through the create service account API.

Changelog: added

EE: true

References

#451032 (closed)

doc/api/user_service_accounts.md

@@ -124,7 +124,7 @@ Example response:
 }
 ```
 
-This will fail if the email address has already been taken by another user:
+This fails if the email address has already been taken by another user:
 
 ```json
 {