tests: add test for frozen_mutation_fragments
tests: add test for frozen_mutation_fragments

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