Add the primary file to EXTRA_INSTALL_ZIPS

Make needs to know the primary file, because the zip is only extracted
when the primary file is installed.

Bug: 337869220
Test: m out/target/product/emu64x/obj/PACKAGING/system_intermediates/file_list.txt and checking it for the extra NetworkStackGoogle apks, with a local NetworkStackGoogle android_app_set added into the tree
Change-Id: I5cb7243d214f4730e3f9efb6746793f3bf4b8214