testutil: check for grpc resources in AfterTest
gRPC leaks only show up at the final leak check, making it difficult to
determine which test is causing the leak.
@@ -76,6 +76,7 @@ func CheckAfterTest(d time.Duration) error {
"net.(*netFD).connect(": "a timing out dial",
").noteClientGone(": "a closenotifier sender",
").readLoop(": "a Transport",
+ ".grpc": "a gRPC resource",
}
var stacks string
