Ensure to close connection to VM after collecting coverage (#50943)

packages/flutter_tools/lib/src/vmservice.dart

diff --git a/packages/flutter_tools/lib/src/vmservice.dart b/packages/flutter_tools/lib/src/vmservice.dart
index 7fc4664..f18f802 100644
--- a/packages/flutter_tools/lib/src/vmservice.dart
+++ b/packages/flutter_tools/lib/src/vmservice.dart
@@ -452,6 +452,8 @@
   Future<void> getVM() async => await vm.reload();
 
   Future<void> refreshViews({ bool waitForViews = false }) => vm.refreshViews(waitForViews: waitForViews);
+
+  Future<void> close() async => await _peer.close();
 }
 
 /// An error that is thrown when constructing/updating a service object.