fix(dsr): change grpc resolver to passthrough

[aauren]

@mrueg

When we used DialContext() before it was deprecated, it manually set the default resolver to passthrough. NewClient() appears to not do this, and then several versions of grpc ago, they defaulted to the DNS resolver which broke our DSR implementation with CRI compatible container engines.

I'm not 100% sure that there isn't a better way to specify this, but I spent 20 - 30 minutes poking around the gRPC code base and I don't think that I can see an easy way to do this outside of specifying it this way.

Furthermore, the project itself seems to advocate for this approach in comments like those on: grpc/grpc-go#1846

Fixes: #1754

[opipenbe]

Hi! This changed resolved DSR issue. I also mentioned in #1754

But seems like I found either bug or feature with the latest master build? :)

With the latest master branch kube-router is starting with an error:
Failed to start node BGP server: failed to start BGP server due to : invalid router-id

In my test environment I am not using IPV6 and I havent previously used --router-id option. Although everything seems working fine once I added --router-id=generate as per https://www.kube-router.io/docs/user-guide/

[aauren]

Yes, sorry, I should have prepped you for that. If you used the build from this pipeline instead of just applying the patch, then you would have hit the regression that I fixed in another PR: #1755

Since both have been reviewed, I plan on merging both today, and then cutting a new release.