Interval between SLURM Queue Checks Set in Multiple Places

[fjclark]

This makes it difficult to change quickly. It should be set in one place only -- probably in the SlurmConfig added in @Roy-Haolin-Du's PR.

[Roy-Haolin-Du]

Thanks Finlay!
I'll make all these hardcoded sleep intervals into the SlurmConfig class to make them centrally configurable.

[fjclark]

Amazing, thanks very much Roy!