Cannon: Refine alerting for vm-runner panics

## Description

Currently, if the vm-runner panics, this is categorized as [a failure to run](https://github.com/ethereum-optimism/optimism/blob/29c83ba3dd575faa3d1cd253d89893d06933a03b/op-challenger/runner/runner.go#L126-L127).  We should instead make sure it is categorized as a panic and add separate alerting for this case. 