slurm-job-exporter no longer works with Slurm 26

Slurm changed the location of job cgroups in version 26, which breaks slurm-job-exporter. 

Slurm 26.05.2 added an option to restore the previous behavior. Until slurm-job-exporter is fixed for Slurm 26, we need to enable that option and use 26.05.2 or more recent. 
https://github.com/guilbaults/slurm-job-exporter/issues/66