Use the same reporter level for flutter and dart runners.

Use the same reporter level across all the tests.

Pre-launch Checklist

[X] I read the Contributor Guide and followed the process outlined there for submitting PRs.
[X] I read the Tree Hygiene wiki page, which explains my responsibilities.
[X] I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
[X] I signed the CLA.
[X] I listed at least one issue that this PR fixes in the description above.
[X] I updated/added relevant documentation (doc comments with ///).
[X] I added new tests to check the change I am making, or this PR is test-exempt.
[X] I followed the breaking change policy and added Data Driven Fixes where supported.
[X] All existing and new tests are passing.

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