Investigate the use of runtime/debug.FreeOSMemory when the app goes in the background

[jrainville]

As found here by @osmaczko , there is a Go function that can force fgreeing the memory from the OS, since the GC can be a bit greedy.

This task is to see if that is a good idea.

[jrainville]

@ilmotta I created this task so we do not forget about testing this. Feel free to move it to the next milestone if you don't think it's doable in 2.34