Integrations - Grafana integration misses the Spans category on Stats Event count

### Problem Statement

Currently when integrated you can pick a Stats -> Category Filter.
This filter lets you choose Transactions however we’ve switched to a new SKU called Spans.
Is it possible to update the integration so we can unblock customers using both Sentry and Grafana?

Transactions still need to be available for people under the old version but the new versions all count through Spans.

### Solution Brainstorm

I've reached out to Grafana but it seems that Sentry PM's have decided to lay down the work on this integration for now.
Hoping we can add the Spans SKU to the grafana plugin

### Product Area

Settings - Integrations