Service Desk - complete mail, when opening a new ticket

This is being tracked on https://gitlab.com/gitlab-org/gitlab-ee/issues/4255

Summary

Currently Gitlab removes forwared content in all e-mails send to the service desk. This is a dealbreaker if the first level support just forwards an e-mail to the service desk, as the content is then removed before it reaches the agent

Steps to reproduce

send you an e-mail via mail, forward that mail to the service desk.

content of the first e-mail is missing

Example Project

none

What is the current bug behavior?

forwared content is lost

What is the expected correct behavior?

forwared content is atleast visible via a <details> / <summary>-tag, so that we can get all the needed information without requesting it again and again.

Relevant logs and/or screenshots

none

Output of checks

none

Results of GitLab environment info

not relevant

Results of GitLab application Check

not relevant

Possible fixes

none