test(e2e): build git-remote-entire with authfilestore too

build:e2e tagged the entire binary but not git-remote-entire. The remote helper imports cmd/entire/cli/auth, so it can reach the keyring-backed auth store and still prompt the OS keychain when e2e flows invoke it (e.g. via a push). Build it with -tags=authfilestore as well so ENTIRE_TEST_AUTH_STORE_FILE routes it to the file backend, keeping the whole e2e environment keychain-free.