User groups with upper case letters are not displayed when editing the "Permission Scheme" details

Summary

User groups with at least an upper case letter can be successfully added to a permission scheme, but are not displayed when viewing its details.

Steps to Reproduce

1. Edit a permission set of a Permission Scheme ("Abandon" in the screenshots)
   
2. Start typing the group name (you'll see every user group in the drop down, including the ones with upper case letters)
   
3. Select a mix of user groups containing only lower case letters and upper case letters ("test_group", "testlowercase", "TestUpperCase" in the screenshot below)
   
4. Check the permission details in the overview, you'll see that every selected group is listed (all groups are lowercase)
   
5. Open the details of the action

Expected Results

All previously selected groups are displayed.

Actual Results

The groups with at least one uppercase letter ("TestUpperCase" in the example) are not displayed.

Notes

The groups are correctly stored in the database and associated to the permission scheme, see the cru_ps_group and cru_ps_id for reference.
Not all permission schemes are affected by this, in general the permissions are still applied as expected even for users belonging to groups with upper case letters with the exception mentioned on CRUC-7678.
This issue is caused by the case-insensitiveness introduced by the FishEye 4.0 user directories.

Workaround

Recreate the groups with only lower case letters.
To restrict Permission Scheme and remove group REST endpoint can be used