Cannot filter Host.Keys logs in v1

From an internal mail:

> One of our customers reached out to us on Stack Overflow calling out the below behavior, Here is the [link](https://stackoverflow.com/questions/57554146/how-to-remove-unnecessary-log-host-keys-are-loaded-from-application-insights/57708111#57708111) for the same:
>
> While using Azure Function 1.x and Application Insights integration, when a Http trigger is called, there is a log: "Host keys are loaded" that is recorded in Application Insights.
>
> Using the below host.json does not help:
>
> ```
> {
> "logger": {
> "categoryFilter": {
> "defaultLevel": "Warning",
> "categoryLevels": {
> "Host.Aggregator": "Information",
> "Function": "Information",
> "Host.Keys": "Error"
> }
> }
> }
> }
> ```
>
> Could you let us know how to stop recording unnecessary logs?

Start by reproducing the HTTP-trigger behavior with the host.json categoryFilter shown in the report and inspect the resulting Application Insights logs. Confirm whether Host.Keys ignores the configured Error level while the other categories retain their expected levels; done means the unwanted Host.Keys entry is filtered in Azure Functions 1.x without breaking the listed categories.

Written by the indexing model from the issue text.