Fix assignee avatar tooltip w special char names

What does this MR do?

This MR fixes an issue where user names that have special characters like ' were being too eagerly escaped in assignee tooltips.

Thanks for pairing on this @leipert @leetickett @cwoolley-gitlab & @markrian! See pairing video on Unfiltered.

Screenshots or Screencasts (strongly suggested)

Before	After

How to setup and validate locally (strongly suggested)

1. Open a MR
2. Assign multiple people including one with a ' in the name
3. Set the one with a ' to either "Busy" or "Cannot merge"
4. Hover over their avatar

• Previous (bug): The tooltip will be too eagerly escape '
• New (fix): The tooltip will show ' properly

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.

References

Related to #227563 (closed)