Read new value of admin status on UserCapabilities update

Before multiple admins were introduced, only main user could be an admin and that status was not modifiable. But now it can be updated for non-main admins of the device. So it is important to refresh this value to keep it up to date.

Bug: 359466920
Test: atest UserCapabilitiesTest
Flag: EXEMPT bugfix_only
Change-Id: If39ad24b10daf6886f402926b3bab23b50201c98