Remove ContextBuilder.onCreateAnalysisDriver.
Remove ContextBuilder.onCreateAnalysisDriver.

It was supposed to be 'temporary plugin support', and I believe we
have a replacement.

Change-Id: I7c6482fa257bee7a7c5c41c47d537b00e8f3ac69
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/186840
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Commit-Queue: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@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