Remove unnecessary ee project select vue file

What does this MR do?

I noticed that we have an EE vue file for project_select.vue that is exactly the same as it's CE version. We should remove the unnecessary redundant EE vue file.

How it happened

• 3 weeks ago app/assets/javascripts/boards/components/project_select.vue was only used in EE but not in CE
• 2 weeks ago https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4633 ran a script to move files that were used only in EE to ee/ prefixed directory
• 1 weeks ago https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17274 brought project_select.vue to CE
• Today we have a CE project_select.vue and an EE project_select.vue (content of both are the same)

Are there points in the code the reviewer needs to double check?

None

Why was this MR needed?

~"technical debt"

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ee/issues/4536