Reduce package cache memory usage.

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