Prepare for removal of legacy-test from default libraries

In preparation for removing junit classes from the Android API
the legacy-test target will be removed from the
TARGET_DEFAULT_JAVA_LIBRARIES. This change adds explicit
dependencies on junit and/or legacy-android-test to ensure that
modules will compile properly once it is removed.

Bug: 30188076
Test: make checkbuild
Change-Id: I33c44d22d3e4e4e86013ce30d244b0bb433eb109