Cherry-pick: Remove deprecated batch concurrency option (#1662)

[GingerAdonis]

Upstream PR

dimitri#1662

Summary

Removes the deprecated batch concurrency parser option which was overriding prefetch rows, causing issue dimitri#1661. Parser rule now only accepts prefetch rows. Removes batch concurrency = 3 from 3 test .load files.

Files

• src/parsers/command-options.lisp
• test/csv-districts-env.load
• test/csv-districts-stdin.load
• test/csv-districts.load

Notes

• Low risk, removes dead code path
• Priority: Medium