Tweak worker numbers for openqaworker-arm-4 and arm-5
With https://gitlab.suse.de/openqa/salt-pillars-openqa/-/merge_requests/353 I added a really conservative, small numbers of workers on our two new arm machines to see if they work at all. If the workers work as expected we need to tweak these numbers further and find the proper limit of worker instances.
Also the multi-machine setup is not yet configured. This should be chanced too (see e.g. arm-3 as reference: https://gitlab.suse.de/openqa/salt-pillars-openqa/-/blob/master/openqa/workerconf.sls#L805-813)