Fixed not shown existing-email warning on new ldap user

- Reduced the amount of different exceptions from LDAP attempt so they
can be handled more consistently.
- Added test to cover.
- Also cleaned up LDAP tests to reduce boilterplate mocks.

Fixes #2048

app/Exceptions/NotifyException.php

@@ -8,8 +8,6 @@ class NotifyException extends \Exception
 
     /**
      * NotifyException constructor.
-     * @param string $message
-     * @param string    $redirectLocation
      */
     public function __construct(string $message, string $redirectLocation = "/")
     {