Stop caching entire ServiceInfo object.

All we care about from the ServiceInfo object is the intended process
name, so cache only that value instead of the entire ServiceInfo object.
The cache is meant to help reduce calls to PackageManager for data that
won't change often.

Bug: 141645789
Test: atest CtsJobSchedulerTestCases
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/job
Change-Id: Ice4aa6dc1a917927ebaf80b0c4a2cba52fe8ed6d