health-check: Don't fail with 3 strings cpu identification

On some processor samples, the cpu name was splitting in 3 parts instead
of 2.
health-check: Fixing string computation

A prior fix introduced a + \ method to concatenate the strings.
This fails at runtime. Fixing by removing the +
health-check: Generic method to get free memory

Regarding the version of python, the method to use to get the free memory isn't the same. So let's use the newest first and if it doesn't exist, let's use the legacy one.
if psutil.virtual_memory().total doesn't exist, let's use the legacy  psutil.avail_phymem() call.