Fixes host_required_modules for test_module_config

We weren't emitting the needed .mk variable for host_required modules.

Test: atest -c CtsLibcoreTestCases_dalvik_system
Test: CtsBackupTestCases_cts_permissiontest
Bug: b/368357047
Change-Id: I6ed7bd6d64dba0ed93f3eead74752911f63276b2