Searching assignable users in assignee field retrieves multiple results when user being searched is registered in multiple directories

Issue Summary

Affects versions of Jira 8.22.0 and later.

When searching for users in the assignee field it has been found that duplicate results will be retrieved if the same user is registered in multiple user directories.

This is reproducible on Data Center: yes)

Steps to Reproduce

1. Create a user in a directory configured in Jira (or synchronize a connected directory where a user is added to Jira.
2. Using the same details create a second user in a different directory.
3. Place directory 2 above directory 1 in the user directories configuration.
4. In an applicable project where the user an assignable user attempt to assign an issue to the user added previously.

Expected Results

• A single result should appear when searching for the user to be selected as the assignee on the issue.

Actual Results

• Multiple results appear for the user being searched as displayed below

• This is a regression introduced because of JRASERVER-73023
• applies to assignable and mentionable user search only
• Restarting jJira does not resolve this as indicated in JRASERVER-68456 since the user cache is not causing the behavior.

Workaround

1. In the search results pick the top one from the list of duplicates as it is the user found in the highest directory in the user directory configuration.
   kcichy: I realised this is not a valid workaround, because the duplicates are sorted by directory id, not directory order as defined in the user directory configuration.
2. Remove user duplicates if feasible