WIP: Fix label filter dropdown edge cases

What does this MR do?

Specifically encode ' rather than encoding all characters as the frontend and ruby encodes characters differently

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

Check for any edge cases that this may not work

Why was this MR needed?

Fixes the following bugs:

• Removing a filter label that contained a space did not get removed from the filter because the space was getting converted into %20
• Double encoding occurs when filtering tags containing spaces in the Issues listing

Screenshots (if relevant)

Before:

After:

Before (removing filter label containing space):

After (removing filter label containing space):

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #21880 (closed), #21935 (closed)