internal: Remove reference to OpenCensus view.

OpenCensus gRPC views are being updated to reflect the latest spec.
Remove a reference to an old view that will not longer exist after
the update, and instead subscribe to the default set of client-side
views.

OpenCensus PR: census-instrumentation/opencensus-go#689

Change-Id: I3308ec22b71c8548e3c7fd39cfad597cab65d241
Reviewed-on: https://code-review.googlesource.com/26370
Reviewed-by: Jonathan Amsterdam <[email protected]>

internal/testutil/go18.go

@@ -35,7 +35,7 @@ func NewTestExporter() *TestExporter {
 
 	view.RegisterExporter(te)
 	view.SetReportingPeriod(time.Millisecond)
-	if err := view.Register(ocgrpc.ClientRequestCountView); err != nil {
+	if err := view.Register(ocgrpc.DefaultClientViews...); err != nil {
 		log.Fatal(err)
 	}