Remove schedule recheck logic from TetherService

This change just remove unused code.
Tethering no longer ask TetherService to schedule recheck
(use #EXTRA_SET_ALARM) from Android Q. Intead Tethering
(EntitlementManager) would schedule the recheck by itself.

This change is necessary in order to move the resourcesout
of the framework because TetherService needs to know when
it need to re-run entitlement recheck from framework res
(config_mobile_hotspot_provision_check_period).

Bug: 146918263
Test: atest TetherSerivceTest
Change-Id: Ie45859c19b96d0689c45dd610501fae0506742ff