Imply sample_watermark -> watermark

Posted under Tags

This tag used to be called sample and was slapped on any random doujinshi page from pixiv, which made it useless. When it was renamed I went through it and removed a lot of posts, but I didn't go through the entire tag, so I'm afraid that approving this as it is would add a lot of mistags to watermark.

I've cleaned up sample_watermark and made a favgroup of things I'm not 100% certain are watermarks. All of them don't obstruct the image and could easily be removed using MS Paint, so I wouldn't call them watermarks imo.
I can't clean up posts that are banned because I can't see them. If those two get cleaned up, then it should be safe to approve this BUR.

I think topic #20734 is worth revisiting because the BUR got rejected likely for the same reason.