Remove recipes from 1.12.13 since stable is now version 1.17.0.

These recipes were already deleted from the builder config in
https://github.com/flutter/infra/pull/121.

Change-Id: I804a30efd3af7fbf35410fb6cd59ce3aeed52c52
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/2660
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Reviewed-by: Tong Wu <wutong@google.com>