telemetry: Remove unnecessary imports
telemetry: Remove unnecessary imports

Bug: https://github.com/dart-lang/sdk/issues/44569
Change-Id: I75ca15c391e0c77840e65d27b26583f15b59eea4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/177340
Reviewed-by: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>
Commit-Queue: Samuel Rawlins <5cf2cac5eec2ad6d0eb2b0f4ff6af9a590ce2bf6@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