Remove mock SLURM Cluster CI step #846

Job	Run time
Run linting/pre-commit checks	22s
unit-tests (ubuntu-latest, 3.9)	2m 0s
unit-tests (ubuntu-latest, 3.10)	1m 59s
unit-tests (ubuntu-latest, 3.11)	1m 48s
unit-tests (ubuntu-latest, 3.12)	1m 55s
unit-tests (ubuntu-latest, 3.13)	1m 51s
unit-tests (windows-latest, 3.9)	2m 24s
unit-tests (windows-latest, 3.10)	2m 28s
unit-tests (windows-latest, 3.11)	2m 41s
unit-tests (windows-latest, 3.12)	2m 49s
unit-tests (windows-latest, 3.13)	2m 37s
unit-tests (macos-latest, 3.9)	1m 41s
unit-tests (macos-latest, 3.10)	1m 41s
unit-tests (macos-latest, 3.11)	1m 42s
unit-tests (macos-latest, 3.12)	1m 45s
unit-tests (macos-latest, 3.13)	1m 31s
integration tests with a mock slurm cluster	0s
integration tests with a real SLURM cluster	0s
Upload coverage reports to Codecov	0s
	31m 14s

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