Fix iterator misuse

Fix a bug where we iterate through a map with an iterator while deleting
some elements (on the map directly, not using the iterator) at the same time.

Bug: 112982695
Test: atest com.android.cts.devicepolicy.MixedProfileOwnerTest#testDelegation
Change-Id: Id46701791d9666ed653683f41e82e3b1d2288432