Introduce uppermost_bound() method instead of upper_bound() in mutation_fragment_filter and clustering_ranges_walker.
For now, this has been only used to produce the final range tombstone
for sliced reads inside consume_partition_end().
Usage of the upper bound of the current range causes problems of two
kinds:
1. If not all the slicing ranges have been traversed with the
clustering range walker, which is possible when the last read
mutation fragment was before some of the ranges and reading was limited
to a specific range of positions taken from index, the emitted range
tombstone will not cover the untraversed slices.
2. At the same time, if all ranges have been walked past, the end
bound is set to after_all_clustered_rows and the emitted RT may span
more data than it should.
To avoid both situations, the uppermost bound is used instead, which
refers to the upper bound of the last range in the sequence.
* github.com/scylladb/seastar-dev.git haaawk/projects/sstables-30/enable-mc-with-sstable-mutation-test/v2
sstables: Use uppermost_bound() instead of upper_bound() in
mutation_fragment_filter.
tests: Enable sstable_mutation_test for SSTables 'mc' format.
Rebased by Piotr J.
(cherry picked from commit b89556512a)
95c5872450