[Question] Why does metricDescriptor have to be created from the app

Hi,

Couldn't find any better place to ask this question (so sorry in advance)

I was just curious to understand what the relationship is between opentelemetry instrumentation and the [Terraform monitoring resource](https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/monitoring_metric_descriptor#argument-reference)?

The `CloudMonitoringMetricsExporter` when sending the metrics also appears to be making requests to create metric descriptors thus requiring the `"roles/monitoring.metricWriter"` permission on the running identity.

but then what is the purpose of the terraform resource? It would have been quite neat if I could just define the metric descriptors through terraform and then have my application use that without having to add additional permissions.

Thanks!
Jonas