test/manual/sstable_scan_footprint_test: run test body in statement sched group
test/manual/sstable_scan_footprint_test: run test body in statement sched group

So that queries are processed in said scheduling group and thus they use
the user read concurrency semaphore.

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla