Delete DE apex data snapshots when rollback is deleted.

This adds a new ApexService method to delete the DE_sys and
DE_user apex data snapshots. This will be called from RollbackManager
when a rollback expires or is otherwise deleted.

Framework counterpart change: ag/10173899

Cherry-pick of internal CL: ag/10180831.

Bug: 141148175
Test: atest ApexService#DestroyDeSnapshots_DeSys (new test)
Test: atest ApexService#DestroyDeSnapshots_DeUser (new test)
Test: manually check snapshots are deleted when rollback expires
Change-Id: I4b33b98f2248cc4fb5c6b4464b9d70cf07dfd0be
Merged-In: I4b33b98f2248cc4fb5c6b4464b9d70cf07dfd0be
6 files changed