Improve Capacity usage on AIX boxes

[sxa]

Ref adoptium/infrastructure#1151

We resolved this resource limit problem by reducing the amount of RAM which the builds script uses for it's calculation. This isn't ideal, and I suspect a preferable solution would be to make use of the NUM_JOBS variable to cap the number of things that can be run in parallel, as this can be controlled more effectively on a per-machine basis using the NUM_PROCESSORS variable we have on most of the machines in jenkins (Although at the moment I'm not sure if this is used by the build processes other than for arm32)

[aixtools]

Commenting - because it is still open (here). Maybe it just needs closing. However, now that the ramdisk is not supposed to be used - the 16G that was used for the RAM disk is available for other work - maybe allowing more memory again.

[karianna]

Yeah can close this and open a new one if required.