Adjust text in issue status header

What does this MR do and why?

Solves #349329 (closed), more exactly follows #349329 (comment 849859482)

This MR changes the text in the issue status header, when an issue is created via Service Desk. In particular, when user sets up Reply-To in their email, in the issue header we see both From and Reply-To email addresses.

Screenshots or screen recordings

Without Reply-To set up:

With Reply-To set up:

Issue list:

How to set up and validate locally

1. See docs for configuring service desk. You need to set up incoming email, which in short is:

2. On gitlab-development-kit, open support/templates/gitlab/config/gitlab.yml.erb:112, enable the incoming_email, and setup your email credentials.

3. From the gitlab project, open the Gemfile, search for the gitlab-mail_room gem and set it to the latest version (at the moment 0.0.19), then run bundle install. Important: do not commit this change, get rid of it once done testing.

4. You can check if the configuration works fine with: bundle exec rake gitlab:incoming_email:check.

5. Run bundle exec mail_room -q -c config/mail_room.yml in a console. This is necessary to receive the email sent to the service desk.

6. After you set up incoming email, follow [steps 2. and 3. here].(https://docs.gitlab.com/ee/user/project/service_desk.html#configuring-service-desk)

7. Send an email to the service desk address, which should be published as a issue in the GitLab UI on Issues > Service Desk.

8. In the incoming email account that you just set up, set up reply-to.

9. Send an email to the service desk address again, to compare.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.