Merge #152979

152979: workload: use same key sequence during KV --insert-count r=RaduBerinde a=jbowens

When inserting an initial --insert-count keys, use the configured key schema to
insert the keys. This ensures that a subsequent call passing an appropriate
--write-seq flag will read the keys inserted through --insert-count.

Fix #107874.
Epic: none
Release note: none

Co-authored-by: Jackson Owens <jackson@cockroachlabs.com>

Author: craig[bot]