Closes #23074

Summary of Changes

If mail is enabled in Joomla config, but we were unable to send the email, the request is created, but the error message states that the request was not created.

There is no point in creating a request if we cannot send the email - this is why mailing has to be enabled. If your mail settings are wrong, the mail cannot be sent, and therefore we should remove the request and inform the user correctly.

Testing Instructions

Default 3.9.0 installation with this PR.
Create a "Create Request" Menu item using Privacy -> Create Request menu type
in Joomla Global Config set:

• Send Mail = Yes
• Mailer = SMTP
• SMTP HOST = NO_SUCH_SERVER
  Login to frontend of the site
  Click Create Request
  Enter email address
  Click submit

Expected result

and NO ROW left in #__privacy_requests

Actual result

(note this error was NOT generated with the above testing instructions, for this one you need to disable mail in php which is harder than the above testing instructions.)

and ROW left in #__privacy_requests even though the error says no request was made.

Documentation Changes Required

None