utils: do not include unused headers

these unused includes were identifier by clang-include-cleaner. after
auditing these source files, all of the reports have been confirmed.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#22201

api/config.cc

@@ -14,6 +14,7 @@
 #include "replica/database.hh"
 #include "db/config.hh"
 #include <sstream>
+#include <fmt/ranges.h>
 #include <boost/algorithm/string/replace.hpp>
 #include <seastar/http/exception.hh>
 

utils/config_file.hh

@@ -10,8 +10,6 @@
 #pragma once
 
 #include <fmt/format.h>
-#include <fmt/ranges.h>
-#include <fmt/ostream.h>
 
 #include <unordered_map>
 #include <string_view>

utils/disk_space_monitor.hh

@@ -8,7 +8,6 @@
 
 #pragma once
 
-#include <chrono>
 #include <filesystem>
 
 #include <boost/signals2/connection.hpp>
@@ -18,7 +17,6 @@
 #include <seastar/core/abort_source.hh>
 #include <seastar/core/future.hh>
 #include <seastar/core/lowres_clock.hh>
-#include <seastar/core/timer.hh>
 #include <seastar/util/optimized_optional.hh>
 
 #include "seastarx.hh"