[Custom Handler] Live metrics memory is wrong

This is linked to #6172

Using the same https://github.com/jdubois/azure-native-spring-function example, the memory usage on my machine is 32 Mb (which is expected).

- When using the "~2" version of the Functions runtime, memory usage is shown as "0 mb", which is obviously wrong.
- When using the "~3" version of the Functions runtime, memory usage is shown as "700 mb". This seems way too much, so I would like to know what exactly causes that. Are you monitoring more than just the process that was created?

This is running on Linux with the consumption plan, I'm going to do more tests, using Windows, to see if there's a difference.