Change test_abandoned_streamed_mutation_from_mutation
Change test_abandoned_streamed_mutation_from_mutation

to test_abandoned_flat_mutation_reader_from_mutation

Signed-off-by: Piotr Jastrzebski <2c0eb4a25a7cde333ff2d0860cb06051925fd74f@scylladb.com>

duarten/scylla,avikivity/scylla,avikivity/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,duarten/scylla,scylladb/scylla