💡 Rename build_info metric to cloudflared_build_info

[Cyb3r-Jak3]

Describe the feature you'd like
The current name of build_info is very generic, which means it can be hard to find or can be easily mixed with other metrics.

Describe alternatives you've considered
Add to add a new label to the metric processing to make it easier to identify.

Additional context
It is a common pattern for other Prometheus metrics exporters. Given it could be a breaking change, might make sense to duplicate it to cloudflared_build_info first.