these unused includes were identified by clang-include-cleaner. after
auditing these source files, all of the reports have been confirmed.
also, took this opportunity to remove an unused namespace alias. and
add an include which is used actually. please note,
`std::ranges::pop_heap()` and friends are actually provided by
`<algorithm>` not `<ranges>`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#22716