[ci.yaml] Add builders to recipes cq

[CaseyHillers]

This enables testing flutter/recipes changes to these builders

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read and followed the [relevant style guides] and ran [the auto-formatter]. (Note that unlike the flutter/flutter repo, the flutter/plugins repo does use dart format.)
• I signed the [CLA].
• The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• I listed at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the [pub versioning philosophy].
• I updated CHANGELOG.md to add a description of the change.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making or feature I am adding, or Hixie said the PR is test exempt.
• All existing and new tests are passing.

[stuartmorgan]

RSLGTM (with one question), since this key isn't documented at https://github.com/flutter/cocoon/blob/master/CI_YAML.md so I'm not entirely sure what it does. (Could it be added there?)

[stuartmorgan]

We want the string true, not the value true?

[CaseyHillers]

Thanks for pointing this out! I'll add it to the docs.

This is a limitation of yaml files backed by proto (we define properties to be Map<String, String> as there's no Map<String, dynamic> option (granted we could do a JsonString of sorts)