fix: fix delay clean logic when multiple healthchecker was started

lib/resty/healthcheck.lua

@@ -1650,9 +1650,11 @@ function _M.new(opts)
         end
 
         local cur_time = ngx_now()
+        local is_checked = false
         for _, checker_obj in pairs(hcs) do
 
           if (last_cleanup_check + CLEANUP_INTERVAL) < cur_time then
+            is_checked = true
             -- clear targets marked for delayed removal
             locking_target_list(checker_obj, function(target_list)
               local removed_targets = {}
@@ -1681,8 +1683,6 @@ function _M.new(opts)
                 end
               end
             end)
-
-            last_cleanup_check = cur_time
           end
 
           if checker_obj.checks.active.healthy.active and
@@ -1701,6 +1701,9 @@ function _M.new(opts)
             checker_callback(checker_obj, "unhealthy")
           end
         end
+        if is_checked then
+          last_cleanup_check = cur_time
+        end
       end,
     })
     if not active_check_timer then