[ Merge of http://go/wvgerrit/164277 ]
No functional changes are made in this CL. policy_timer_v16 and
policy_timer_v15 derive from policy_timer. We have removed
support for OEMCrypto v15. policy_timer_v15 has also been removed.
This allows us to move functionality from policy_timer_v16
to policy_timer class. This will ease subsequent renew on
license load functionality.
Bug: 256038127
Test: Luci tests
Change-Id: Iebd588237edd02b30a820c4d9d57ce041c26964e