csi: restore long timeout for controller plugins

During MVP development, we reduced the timeout for controller plugins
to avoid long hangs in GC workers. But now that this work has been
moved to the volume watcher, we can restore the original timeout which
is better suited for the characteristic timescales of some cloud
provider APIs and better matches the behavior of k8s.

client/csi_endpoint.go

@@ -143,12 +143,12 @@ func (c *CSI) ControllerDetachVolume(req *structs.ClientCSIControllerDetachVolum
 	csiReq := req.ToCSIRequest()
 
 	// Submit the request for a volume to the CSI Plugin.
-	ctx, cancelFn := context.WithTimeout(context.Background(), 30*time.Second)
+	ctx, cancelFn := c.requestContext()
 	defer cancelFn()
 	// CSI ControllerUnpublishVolume errors for timeout, codes.Unavailable and
 	// codes.ResourceExhausted are retried; all other errors are fatal.
 	_, err = plugin.ControllerUnpublishVolume(ctx, csiReq,
-		grpc_retry.WithPerRetryTimeout(10*time.Second),
+		grpc_retry.WithPerRetryTimeout(CSIPluginRequestTimeout),
 		grpc_retry.WithMax(3),
 		grpc_retry.WithBackoff(grpc_retry.BackoffExponential(100*time.Millisecond)))
 	if err != nil {