This reverts commit 4bbf158b.

* Revert "add Podfile (#9835)"

This reverts commit 74e65675.

* Revert "update ref to url_launcher plugin in Flutter Gallery (#9833)"

This reverts commit 30c49781.

* Revert "Use url_launcher plugin in Flutter Gallery (#9751)"

This reverts commit 02dfd6be.

Enable plugin infra for both iOS and Android post-#9791.

Brings hello_world and flutter_gallery Android code in line with the
corresponding iOS code.