Remove redundant `--template` arguments from code samples (#30909)

This removes redundant --template arguments from the samples that I should have removed before in #30827 .

Also, fixed a bunch of spelling misteaks.
https://dart.googlesource.com/external/github.com/flutter/engine/+/70024475f41a7cb311e721bf10d95354510c57ab
1 file changed
tree: 977c798cd88693571066009aff64cdcfca92d967
  1. commits.json