otel: retries must be tracked per-call and not per-attempt

[easwars]

The number of retries is currently tracked inside the attemptInfo here:

grpc-go/stats/opentelemetry/opentelemetry.go

Line 244 in e816736

previousRPCAttempts uint32

And a new attemptInfo is created for every attempt here:

grpc-go/stats/opentelemetry/client_metrics.go

Line 155 in e816736

func getOrCreateRPCAttemptInfo(ctx context.Context) (context.Context, *attemptInfo) {

We need to track this in the callInfo instead, so that we can increment the number of retries for a call:

grpc-go/stats/opentelemetry/opentelemetry.go

Line 174 in e816736

type callInfo struct {

We had a PR that attempted to do this earlier: #8342, but it introduced a flaky test and therefore had to be rolled back.

[easwars]

Also tracked in an internal issue 459640710.

[ulascansenturk]

Hello @easwars, could you assign this to me?

[easwars]

Hello [@easwars](https://github.com/easwars), could you assign this to me?

You got it!

[ulascansenturk]

Thanks @easwars
opened the pull request #8715