Remove `v1` and `v2` Endpoints

[Sneagan]

We no longer use these versions. Verify the metrics match this expectation and then remove them from the service.

This is a 2-phase task:

1. Verify that the endpoints are no longer used with the new prometheus metrics
2. Release a version that returns 426 Upgrade Required on these endpoints if the metrics indicate non-zero but low usage
3. Release a version without these endpoints altogether