Scale task snapshots to very small on low RAM.

This CL scales snapshots down when the lowRamTaskSnapshotsAndRecentsFlag
flag is set as this version of recents uses much smaller snapshots.

Bug: 114136250
Test: manual
Test: atest TaskSnapshotPersisterLoaderTest
Test: atest TaskSnapshotCacheTest
Test: atest TaskSnapshotControllerTest
Change-Id: I34d1d6c91fae31cfe677aa24edae185554e5bf7c