## Description
Removes the following deprecated Prometheus metrics:
- `coderd_api_workspace_latest_build_total` → use
`coderd_api_workspace_latest_build` instead
- `coderd_oauth2_external_requests_rate_limit_total` → use
`coderd_oauth2_external_requests_rate_limit` instead
These metrics were deprecated in #12976 because gauge metrics should
avoid the `_total` suffix per [Prometheus naming
conventions](https://prometheus.io/docs/practices/naming/).
## Changes
- Removed deprecated metric `coderd_api_workspace_latest_build_total`
from `coderd/prometheusmetrics/prometheusmetrics.go`
- Removed deprecated metric
`coderd_oauth2_external_requests_rate_limit_total` from
`coderd/promoauth/oauth2.go`
- Updated tests to use the non-deprecated metric name
Fixes#12999
Marcin Tojek
036ed5672f