spanner: support custom meterprovider for builtin metrics

## Is your feature request related to a problem? Please describe.

Spanner client is sending builtin/native metrics directly to GCP by default.

For services that have no permission, the metric export results to error log and span with following message.
> Permission monitoring.timeSeries.create denied (or the resource may not exist).

For the above noise to go away, the native metrics can be disabled (SPANNER_DISABLE_BUILTIN_METRICS=true) or simply give service the missing permission. However, this is always something to keep in mind for a new service using spanner.

## Describe the solution you'd like

Use the ClientConfig.OpenTelemetryMeterProvider from the config

Code affected.
https://github.com/googleapis/google-cloud-go/blob/5b59819e2d603ef55c4cf056b70af6a08d335373/spanner/client.go#L496-L511

## Describe alternatives you've considered

- Allow a param that sends builtin metrics to the global meter provider `otel.GetMeterProvider()`

## Additional context
Add any other context or screenshots about the feature request here.