Change the resource cache key from context to package name.

Multiple contexts can be created in one application, and redundant
caches can be accumulated if resources are cached by each context.
Change the one of resource cache key from context to package name
to avoid stacking caches.

Bug: 289045241
Test: atest CtsTelephonyTestCases:SubscriptionManagerTest
Change-Id: I0d4b17b1157d6f453213de864d00beffc2d628c4