Unable to change outgoing mail server from Oauth to Basic Auth

Issue Summary

When you try to modify the outgoing mail server going from Oauth authentication to basic authentication, it does not save the configuration.

This is reproducible on Data Center: (yes)

Steps to Reproduce

1. Configure the connection in the Application Links to your mail server.
2. In Outgoing Mail, configure a mail server to use Oauth 2.0 authentication.
3. Test the connection and save.
4. Now modify the email server to use basic auth.
5. You will notice that the button still says "Save and authorize"
6. If you click again, the settings will still be showing the Oauth 2.0 as the authentication method.

Expected Results

Upon modifying the configuration, Jira should save and work.

Actual Results

Jira is not saving the new configuration and prevent the notifications from working.

Workaround

Delete the email configuration and start from scratch.