fix(redisotel): correct metrics.DialHook attrs

[scott20315]

• pass attrs by value instead of by reference to the otel histogram Record function
  • the histograms in the otel sdk perform an in-place sort on the attrs passed into Record
  • a race condition can occur when separate goroutines concurrently interact with the various redisotel hooks
  • this PR converts the dialhook to a read operation which is consistent with the behavior of the other hooks
• side benefit of including the error status attr which is another step towards consistency with the other hooks

[monkey92t]

I don't know about metrics...
It looks like it's just missing handling err.

[monkey92t]

seems to be ok.