Add button still enable when cancel select user to group

• Type: Regression Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.3.0 CE GA1, Master
• Component/s: Item Selector, User Management > User Groups
• Labels: None
• Story Points: 1
• Fix Priority: 3
• Last Working Version:
  7.2.10 DXP FP3
• Sprint: LIMA | #09 | Dec10-Dec20
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/82166

Steps to reproduce:

1. Go to Users > User Groups
2. Add a group
3. Assign a user to group
4. Select Test Test to assert the Add button is enabled, that's right
5. Cancel select Test Test to assert the Add button is disabled

Expected results: Add button is disabled after canceling select.
Actual results: Add button is enabled after canceling select.

Note: When assigning user to teams, have this issue too.