Closes https://github.com/flutter/flutter/issues/163706.
Before this PR, the macOS workflow (or, others, but only macOS had a
test) would fail because it calls `refreshPluginsList` manually, and
sometimes it would be `determineDevDependencies: null` and sometimes
`determineDevDependencies: false`.
A value of `determineDevDependencies: null` was interpreted later on as
"find dev dependencies", which is not a safe operation. The only real
change in this PR is `bool determineDevDependencies = false`, so
omitting that parameter means we don't determine dev dependencies.
Added some tests, and opted-in an integration test that was failing.
281612e648