Add config_reducedTaskSnapshotScale

Add config_reducedTaskSnapshotScale to replace previously hardcoded
value of 0.5.

Test: TaskSnapshotPersisterLoaderTest
Test: TaskSnapshotCacheTest
Bug: 148092712
Change-Id: Ib414d244bda02544a52164aee64b73434d5e5631
3 files changed