telemetry: Remove unnecessary imports

Bug: #44569
Change-Id: I75ca15c391e0c77840e65d27b26583f15b59eea4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/177340
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Samuel Rawlins <[email protected]>

Author: srawlins

pkg/telemetry/test/telemetry_test.dart

@@ -6,7 +6,6 @@ import 'dart:io';
 
 import 'package:telemetry/telemetry.dart';
 import 'package:test/test.dart';
-import 'package:usage/usage.dart';
 
 void main() {
   group('telemetry', () {