Delete snapshots after restore is done successfully (1/n)

The snapshots are no longer needed after restore is done.

We do this in keeping with the fact that apk/apex code data is deleted
immediately after the rollback is committed.

APK Snapshots will be handled in the next CL.

See go/rollbackmanager-snapshot-deletion for more details.

(Cherry-picked from d037d0fada1ab6ed534c5b3d3e460496b0f9d623)

Bug: 151805360
Test: atest ApexServiceTest

Merged-In: Ie2609d0a1d2f647227e3704cf8fbd01e0dd7f2e0
Change-Id: Ie2609d0a1d2f647227e3704cf8fbd01e0dd7f2e0
3 files changed