Review the loglevels used

[hejung]

Some loglevels used feel a bit too noisy, e.g. it is probably not needed to log an info message every time we submit a slurm job as we can be submitting quite a lot of jobs when using asyncmd to its full potential.

While doing this doing this one should also make sure that all logging calls use the best practice calling convention, i.e. no f-strings, no + to concatenate, and fill in all variables via the arguments to the logging call.

This should be a good first issue, because it entails reading the code and thinking about it, but all changes only affect logging behavior so you can not really break anything. Since all changes are local it also nicely splits into doing it for one submodule/file at a time.