Remove the cache_time_info option

The new time info caching behaviour supersedes this by getting rid of
callbacks altogether.

src/plugin/bridges/common.h

@@ -175,9 +175,6 @@ class PluginBridge {
 
         init_msg << "other options: ";
         std::vector<std::string> other_options;
-        if (config.cache_time_info) {
-            other_options.push_back("hack: time info cache");
-        }
         if (config.editor_double_embed) {
             other_options.push_back("editor: double embed");
         }