Update paths

[leonhardhennig]

https://pegasus.dfki.de/posts/maintenance_23_24/ states that some directory locations have changed, e.g. /netscratch/enroot has moved to /enroot. Paths in the scripts should be updated according to the status update.

Main changes probably:

• update /netscratch/enroot to /enroot (mostly used as srun arg, "--container-image=/enroot/")
• add /fscratch as image mount, i.e. sth like "--container-mounts=/netscratch:/netscratch,/fscratch/$USER:/fscratch/$USER,/ds:/ds,...