Remove deprecated BazelWorkspace.
Remove deprecated BazelWorkspace.

Change-Id: I656f3c906cdaeb2b7a5ab93c7ccde9693e9a9cba
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/255549
Reviewed-by: Samuel Rawlins <5cf2cac5eec2ad6d0eb2b0f4ff6af9a590ce2bf6@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