Increase buildah nofiles ulimit

Chromium is failing to compile reporting:

obj/components/feedback/libfeedback.a: error adding symbols: malformed archive

which https://github.com/OSSystems/meta-browser/issues/194 has led me to
believe is actually due to the max open file limit.  Checked
`/proc/<buildah-chroot-pid>/limits` inside the build container and, sure
enough, "1024."
4 jobs for main in 152 minutes and 15 seconds
Status Job ID Name Coverage
  Build
passed Build haswell-workstation #436
nest

02:32:15

failed Build haswell-workstation #433
nest

04:46:30

failed Build haswell-workstation #434
nest

01:52:12

failed Build haswell-workstation #435
nest

03:34:51