* Revert "Update Hello World to latest iOS project template (#8634)"

This reverts commit 6dc6ed4e.

* Revert "Update Gallery to latest iOS project template (#8637)"

This reverts commit 84c42aac.

* Revert "Update Stocks to latest iOS project template (#8640)"

This reverts commit 90774c18.

Almost all real-world apps will want a custom app delegate, and 'flutter
create' code-gens one by default. This brings the samples in line with
our templates and the most common use case.