More vendoring updates
Update vendor google.golang.org/grpc
- Update to to v1.13.0.
Remove unused vendoring.
- google.golang.org/grpc/grpclb/grpc_lb_v1/messages
- golang.org/x/net/context/ctxhttp
Update vendor github.com/grpc-ecosystem/go-grpc-prometheus
- Update to v1.2.0.
Fixup vendor github.com/rafaeljusto/redigomock
- Select current v2.1 release.