Factor issue and MR edit form error list.
Created by: cirosantilli
Direct continuation to https://github.com/gitlabhq/gitlabhq/pull/7678
This one factors the error messages.
Note: I am unable to view the error messages, because the only thing that could generate an error, an empty title, is not allowed by the browser because of the "required: true", so I could not test it the CSS looks good.
If anyone knows of a way to do this test, please tell me.
In any case, that is basically dead code, and now it is factored dead code.