Migrate all the places that used memtable::make_reader to use
memtable::make_flat_reader and remove memtable::make_reader.
* seastar-dev.git haaawk/remove_memtable_make_reader_v2_rebased:
Remove memtable::make_reader
Stop using memtable::make_reader in row_cache_stress_test
Stop using memtable::make_reader in row_cache_test
Stop using memtable::make_reader in mutation_test
Stop using memtable::make_reader in streamed_mutation_test
Stop using memtable::make_reader in memtable_snapshot_source.hh
Stop using memtable::make_reader in memtable::apply
Add consume_partitions(flat_mutation_reader& reader, Consumer consumer)
Add default parameter values in make_combined_reader
Migrate test_virtual_dirty_accounting_on_flush to flat reader
Migrate test_adding_a_column_during_reading_doesnt_affect_read_result
Simplify flat_reader_assertions& produces(const mutation& m)
Migrate test_partition_version_consistency_after_lsa_compaction_happens
flat_mutation_reader: Allow setting buffer capacity
Add next_mutation() to flat_mutation_reader_assertions
cf::for_all_partitions::iteration_state: don't store schema_ptr
read_mutation_from_flat_mutation_reader: don't take schema_ptr
Migrate test_fast_forward_to_after_memtable_is_flushed to flat reader
(cherry picked from commit b0a56a91c2)
0a82a885a4