category-ads: clean up and enhancement #2909
                
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There are many problematic/unreliable/stale ad rules in this repo. Some seem to be from other old/dead adblcok projects (e.g. yhosts). It's hard for *ray users to locate/fix problems related to wrong blockings, and few person tried to update these rules or report bugs.
The principle of this pr is removing problematic/unreliable/stale rules and keeping/adding explicit/safe ones, which should be more suitable for the situation in *ray.
This pr may causing some reduction in blocking effectiveness while improving accuracy. Please comment if you have any objections/suggestions, or I'll merge this in a month.