This leaves only the existence of binderservicedomain attribute as
public API. All other rules are implementation details of this
attribute's policy and are thus now private.

Test: No change to policy according to sesearch, except for
      disappearance of all allow rules to do with *_current targets
      referenced in binderservicedomain.te.
Bug: 31364497
Change-Id: Ic830bcc5ffb6d624e0b3aec831071061cccc513c