Merge branch 'remove-research-template' into 'master'

Delete Research proposal.md

See merge request gitlab-org/gitlab-ce!23322

.gitlab/issue_templates/Research proposal.md

-### Background:
-
-(Include problem, use cases, benefits, and/or goals)
-
-**What questions are you trying to answer?**
-
-**Are you looking to verify an existing hypothesis or uncover new issues you should be exploring?**
-
-**What is the backstory of this project and how does it impact the approach?**
-
-**What do you already know about the areas you are exploring?**
-
-**What does success look like at the end of the project?**
-
-### Links / references:
-
-/label ~"UX research"