`partition_reversing_data_source` uses `continuous_data_consumer`s
internally (`partition_header_context`, `row_body_skipping_context`)
which hold `input_stream`s opened to sstable data files. These
`input_stream`s must be closed before destruction. Right now they would
sometimes cause "Assertion `_reads_in_progress == 0' failed" on
destruction.
Close the `continuous_data_consumer`s before they are destroyed so they
can close their `input_stream`s.
Fixes#9444.
Closes#9451
339b9bc38a