Update nextflow.config to latest findings

On our slurm cluster the USER-Variable is not set when only passing the proxy
env variables. So this variable has to be passed as well.

nextflow/nextflow.config

 process {
-  container='ubuntu:24.10'
+  container='ubuntu'
   executor='slurm'
-  clusterOptions="--export=http_proxy,https_proxy,ftp_proxy"
+  clusterOptions="--export=http_proxy,https_proxy,ftp_proxy,USER"
   queue='bcf'
 }
 podman {
   enabled=true
+  engineOptions="--cgroup-manager=cgroupfs"
 }