This change modernizes the codebase by: - Replacing Boost's indexed adaptor with C++20's std::views::enumerate - Removing unnecessary Boost header inclusion With this change, we can: - Reduce external dependencies - Leverage standard library features - Improve long-term code maintainability Signed-off-by: Kefu Chai <kefu.chai@scylladb.com> Closes scylladb/scylladb#22469