PHPMailer: Remove use of class.phpmailer-lite.php
Backport of https://we.phorge.it/D25723 (except for deletion of the file) to get more testing. To revert if mail started to fail.
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Backport of https://we.phorge.it/D25723 (except for deletion of the file) to get more testing. To revert if mail started to fail.