Rename weighted_round_robin_experimental into weighted_round_robin

[atollena]

The weighted_round_robin balancer name has the experimental suffix in Golang, so that it must be referred to as weighted_round_robin_experimental. Java (code) and C-core (code) both use weighted_round_robin without the suffix. The predefined oneof in service config protobuf definition also uses weighted_round_robin (code). As a result, services that wish to use weighted_round_robin in Go have to use a service config loadBalancerConfig of the form:

loadBalancerConfig: [
  {
    name: "weighted_round_robin"
  },
  {
    name: "weighted_round_robin_experimental"
  }
]

and duplicate the parameters.

This issue tracks renaming weighted_round_robin_experimental to weighted_round_robin.

See #6241 from @dfawley, which I suppose introduced it with the suffix for a reason.

[dfawley]

The "experimental" suffix is there to allow sufficient time for testing & validation. It has passed all our internal validation, so I can remove the suffix.

[atollena]

Thanks for your answer, I just saw #6477 which I assume will land in 1.57 or 1.58.

[dfawley]

Yes, I'll put this in the 1.57 release, which should happen today.