The cassandra-stress tool is no longer part of the default package
and cannot be run in the way described.
This commit removes the instruction to run cassandra-stress.
Fixes https://github.com/scylladb/scylladb/issues/24994
Closes scylladb/scylladb#27726
(cherry picked from commit 624869de86)
Closes scylladb/scylladb#27951