Improve delta table memory footprint

[sh-rp]

Currently we write all jobs for one delta table in one write in a referencejob that references all jobs.
There seems to be a problem in the delta rust implementation that materializes all tables in memory before writing them to the destination:

delta-io/delta-rs#2968 (comment)

Possible ways to fix this:

• Create multiple followup jobs per table and control the amount of jobs assigned in each via a setting. Ensure we only process one job per table in parallel if this is set. (loader_parallelism_strategy=table-sequential)
• User other engine than rust, because rust seems to have this problem. Merge does not work there though atm.