Move EXTRA_SERVICE_STATE from Intent to ServiceState.

This extra is not exposed and is not used by anyone as such.
Leaving it there for internal use/unsupported app usage.

Test: basic sanity
Bug: 140908357
Merged-in: I9fe6e904291affb1cd7b705212d47525b61a5679
Change-Id: I9fe6e904291affb1cd7b705212d47525b61a5679
(cherry picked from commit bb61b17c)