Remove useless generic argument and unchecked cast

There is no need for <V> generic parameter - it is not used in either
arguments or result.
The cast is unchecked and in fact uses a wrong type - PolicyDefinitions
are never prarametrized by PolicyValue.

Test: TH
Flag: EXEMPT - the code should result in the same binary
Bug: 335663055
Change-Id: Ia2254808107383a1b8549d0c2d55bf59878b507d