Remove deprecated project kwarg in Cluster implementation, or use it as it should be

Initially, `project` kwarg was used in PBS, SGE and SLURM Cluster implementations to position the `account` (or `-A`) options of each job scheduler. As there is also a real `project` option in some of them, it has been renamed to `account`, but the previous kwarg was kept for backward compatibility with a Warning.

It is now time either to remove completly the kwarg there, or use it correctly for what it means in each HPC Scheduler glossary.

See https://github.com/dask/dask-jobqueue/pull/586 for history.