[multiple] format code

[cyanglaz]

Apply new format rules to some dart files.

This fixes the flutter -> plugin roll

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. (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, or this PR is exempt from version changes.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[flutter-dashboard]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat (don't just cc him here, he won't see it! He's on Discord!).

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

[cyanglaz]

No need to update version because all the files are test files

[stuartmorgan-g]

You'll need to include the roll in this so that format passes.

[cyanglaz]

Flutter roll included: #6235

[Hixie]

test-exempt: reformat

[cyanglaz]

Not sure why publishable keeps failing, we have both override labels on.
@stuartmorgan

[stuartmorgan-g]

Looks like a Cirrus bug. I filed cirruslabs/cirrus-ci-docs#1054

If we don't have a fix on Monday I'll just revert the debugging here and we can force-land this.

[stuartmorgan-g]

Landing manually since the Cirrus issue is not resolved yet.