Deprecate IntentService

IntentService always had some issues, such as delivering null, adding
latency, inconsistently silently dropping tasks scheduled on its thread
local handler, etc. But with android O's background task restrictions,
it's really not useful anymore, and there are jetpack APIs that provide
its same functionality.

Bug: 144042891
Test: No behavior changes
Change-Id: I1a91afeeb73e270c54a9ec266b15b5d865ef8339