Simplify coexistence gating logic

- repurposed the policy engine flag for financed APIs only
- used permission flag for the all other APIs
- removed target sdk logic
- removed coeixstence flag logic

Bug: 273494642
Test: btest a.d.c.DeviceManagementCoexistenceTest
Change-Id: Id3c16654f7d7d766073db7ec427619d7ebdcd784