Enable prometheus lifecycle API to support config reloading

[overvenus]

Feature Request

Is your feature request related to a problem? Please describe:

Support reloading Prometheus config.

https://prometheus.io/docs/alerting/latest/configuration/#configuration

Describe the feature you'd like:

Enable Prometheus lifecycle API via --web.enable-lifecycle to trigger reloading by HTTP requests.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy: