fix(health_server): use rackup handler instead of rack handler

Gemfile

@@ -28,6 +28,7 @@ gem "nio4r"
 gem "ostruct"
 gem "prometheus-client"
 gem "puma"
+gem "rackup"
 gem "rails", "= 7.1.5.2"
 gem "resolv"
 gem "secure_headers"