Add an integration test point for mainline beta exported mode codegen

Mainline beta exported mode codegen will use the same exported
template which relies on new storage. The template is already tested by
existing exported mode codegen integration tests. Here add a test point
to ensure that for mainline beta exported mode, it will builds fine and
runs fine.

Bug: b/406508083
Test: atest -c
Change-Id: Id2bd27dcb53b5f600ab2f94567b73f1759745371