sstables_manager::get_component_lister() is used by sstable_directory.
and almost all the "ingredients" used to create a component lister
are located in sstable_directory. among the other things, the two
implementations of `components_lister` are located right in
`sstable_directory`. there is no need to outsource this to
sstables_manager just for accessing the system_keyspace, which is
already exposed as a public function of `sstables_manager`. so let's
move this helper into sstable_directory as a member function.
with this change, we can even go further by moving the
`components_lister` implementations into the same .cc file.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#13853
03be1f438c