This series gets rid of the remaining usage of flat_mutation_reader v1 in compaction
Test: sstable_compaction_test
Closes#10454
* github.com:scylladb/scylla:
compaction: sanitize headers from flat_mutation_reader v1
flat_mutation_reader: get rid of class filter
compaction: cleanup_compaction: make_partition_filter: return flat_mutation_reader_v2::filter