replace: Force containers to use image's entrypoint

Before, we would copy the previous container's entrypoint when
replacing, causing the `dksnap` boot script to not get run.

info.go

@@ -250,6 +250,9 @@ func (ui *infoUI) replaceContainer(ctx context.Context, old Container, snap *sna
 		containerConfig.Image = snap.ImageNames[0]
 	}
 
+	// Force the container to use the snapshot's entrypoint.
+	containerConfig.Entrypoint = nil
+
 	networkingConfig := &network.NetworkingConfig{
 		EndpointsConfig: old.NetworkSettings.Networks,
 	}