Mixed builds is supported for all apex module types, not just "apex".

This includes apex_test and apex_vndk. Rely on mixed builds module
allowlist to filter further.

Test: presubmits
Test: m test_com.android.adbd; showcommands test_com.android.adbd | tail -n1 | grep bazel-out
Change-Id: Id73db0917ad4a6dd9c0646d5186753ed940e735f