Redact quick action on incoming service desk emails

We gave permission to support bot user perform quick action commands on !21948 (merged). This was made to allow quick actions present on service desk issue templates be processed, more information on #2030 (closed).

Now because quick actions present on the email body sent to service desk could also be processed we had to strip them from the email before creating service desk issues/notes. However removing the quick action from emails is not the ideal solution because in rare cases users could want to specifically mention quick actions.

More information on: !21948 (comment 262488082)

Possible solutions

Instead of removing the quick actions from the email we could enclose them into code span markdown /title example.
This would allow the quick action in the text to still be present but not be processed.

Code that strips quick actions from the email can be found on ::EE::Gitlab::Email::Handler::ReplyProcessing