Add nnbd_migration unit tests to analyzer bots
Add nnbd_migration unit tests to analyzer bots

Change-Id: Id5c7ca2a88933e127e26ddffe3b665bf138330b9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/145503
Commit-Queue: Paul Berry <72d414e3a99fb120308437779d51667bcc0984eb@google.com>
Reviewed-by: Alexander Thomas <29642742b6693024c89de8232f2e2542cf7eedf7@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk