apex-libs-absence checks are removed

The check is implemented in Soong via the apex_available property.
For a module that should be in the APEX named "foo" and shouldn't be in
any other APEX and also in the platform (the non-updatable part), the
property can be set to "foo" (without "//apex_available:platform")
to express the restriction and then Soong will enforce it.

Bug: 128708192
Test: m
Change-Id: Ia1aaaacd685f466447b61deae2849cb0aa83def3