zuul-merger: increate maximum open files
zuul-merger: increate maximum open files

This changes increate the resource limit nofile like it is done in puppet-zuul upstream

Change-Id: I300b4e453ce46d17e54a6ef254704ef96fd13e4d
Fixes-Bug: #1574

enovance/software-factory,enovance/software-factory,enovance/software-factory,enovance/software-factory,enovance/software-factory