Switch to new grpc/http_reliability metrics
Switch to new grpc/http_reliability metrics

- grpc_reliability affects consumption of logs by components
- http_reliability affects consumption by end users/apps

[#161894168] Log cache metric missing for past days in Datadog

Signed-off-by: Jesse Malone <c929decda31f28e677c5c623b33cb23472ce0fde@pivotal.io>

pivotal-cf-experimental/datadog-config-oss,pivotal-cf-experimental/datadog-config-oss