Replace health check server with a normal HTTP server

[hu55a1n1]

Summary

Simplifies the impl and makes it so we don't need to use the grpc_health_probe.

[MSalopek]

Additional context:
quartz does not implement proto reflection interface so you cannot query the grpc address with a request about information. I had to do some digging but I eventually found where the proto file that grpc_health_probe uses and how to use it:

# Download the standard health.proto
curl -o health.proto https://raw.githubusercontent.com/grpc/grpc-proto/master/grpc/health/v1/health.proto

# check for quartz health
grpcurl -plaintext -proto health.proto -d '{"service":"quartz.Core"}' localhost:11090 grpc.health.v1.Health/Check

We would need to add this proto or enable reflection if we want to use grpc.

This happens when you want to request server info with grpc (or other tools):

grpcurl -plaintext localhost:11090 grpc.health.v1.Health/Check

Error invoking method "grpc.health.v1.Health/Check": failed to query for service descriptor "grpc.health.v1.Health": server does not support the reflection API