Remove project select dropdown from breadcrumb

What does this MR do?

This MR is part of the changes added in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/13866, where Projects select dropdown shown in project path breadcrumb is to be removed in favour of dropdown which will be shown in Projects menu on main navigation.

Why was this MR needed?

This MR removes unnecessary dropdown shown in breadcrumb area as that functionality is replaced with Projects dropdown menu on main navigation.

Screenshots

Before (with chevron for opening dropdown)

After (no dropdown)

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

What are the relevant issue numbers?

Closes #35010 (closed)