Remove test_com.android.neuralnetworks from apex_available

In order to simplify the apex logic in Soong, avoid needing to mention
test apexes in apex_available by setting apex_available_name in the
test apex to masquerade as the corresponding non-test apex.

Bug: 383592644
Test: builds
Change-Id: I49f028af371b169558fd6b4217ee6696bb24a7ce
2 files changed