Enhacement Request: Align by default Xmx to container memory

[alexandrev]

Nowadays memory of the AppNode is not aligned with the value from the pod/container which generates some issues at the customer who needs to be monitoring it in order to not forgot to do it.

As we don't support Java 10 yet, we should provide some of the options here as default configuration:

https://medium.com/adorsys/jvm-memory-settings-in-a-container-environment-64b0840e1d9e

What do you think about it?

[alexandrev]

I've seen that with these change we can do it enabling MEMORY_LIMIT env variable

What do you think about @awagle