Reduce timeout for DL to destroy.

10secs should be more than enough to stop whatever the DL is doing.
Besides, DL has its own set of IncFS FDs and should not crash.

Bug: 189222575
Fixes: 189222575
Test: atest IncrementalServiceTest
Change-Id: I73cb27d61c7418adeea7536c8263e6ba8c77fd3e