Move staleness check to new endpoint

[jayantk]

I made the staleness parameter an argument to the endpoint also, so we can configure it directly via the alert in datadog without redeploying the service.

I can't figure out how to build / run this code, so would love some help with that.

[cctdaniel]

you'll have to:

• install docker
• install kubectl
• install minikube
• install tilt
• cd pyth-crosschain
• run minikube start --driver=docker --kubernetes-version=v1.22.3 --cpus=$(nproc) --memory=16G --disk-size=120g --namespace=wormhole
• run tilt up -- --pyth (it'll take ~30mins when you run this the first time as it builds a bunch of services, subsequent runs will be faster since it'll be cached)