Do not inherit when calling const_get

Otherwise we will get really confusing behavior in development
environment (where eager_load is false) where it attempts to load
`Prometheus::Queries::EnvironmentQuery` when query_class_name is
`Gitlab::Prometheus::Queries::EnvironmentQuery`, the `Prometheus` module
is loaded from a gem but not anything in `Gitlab::Prometheus`.

app/models/concerns/prometheus_adapter.rb

@@ -36,7 +36,7 @@ module PrometheusAdapter
     def calculate_reactive_cache(query_class_name, *args)
       return unless prometheus_client
 
-      data = Kernel.const_get(query_class_name).new(prometheus_client_wrapper).query(*args)
+      data = Kernel.const_get(query_class_name, false).new(prometheus_client_wrapper).query(*args)
       {
         success: true,
         data: data,