Only retain the information TARE cares about so we don't waste memory.
The cache serves to reduce the number of calls to PackageManager,
especially while the device is charging.

Bug: 239951405
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/tare
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/tare
Change-Id: I9e345cc3a88c192e00d401a93cbbe0df74f1596b