The issue template for bugs has a notice at the start that mentions to
search for duplicates before creating a new issue. Then the reporter
is asked to remove the notice once read, presumptively to avoid noise
in the actual issue.

Instead of that, we can make that part of the issue template an html
comment, so it won't be rendered in the final result. This avoids
the tedious task of removing that part of the notice.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/43580

[skip ci]

* Bugs reported in the GitLab Issue trackers should be reproducible
* Asking reporters to reproduce on GitLab.com is reasonable
  * It lets us know whether the issue still exists in latest
  * It ensures that the steps to reproduce are solid
  * It gives Developers a live example to work from
  * Reporter can verify the fix in the example project once shipped

[skip ci]

[skip ci]

[ci skip]

Signed-off-by: Rémy Coutable <remy@rymai.me>

Triple backticks aren't allowed inside <details> elements, so add an explicit
<pre> instead.

[ci skip]

Signed-off-by: Rémy Coutable <remy@rymai.me>

Change to use a better title style

Add backticks to code segments

Spelling and Grammar

Adjust bug template to adhere to standard bug report format

* https://developer.mozilla.org/en-US/docs/Mozilla/QA/Bug_writing_guidelines
* Guidelines use the following format

- Summary
- Steps to Reproduce
- Expected Behaviour
- Actual Behaviour

* Include "Bug" template from the contribution guide
* Include "Feature Proposal" template from the contribution guide