DEV: Remove SiteSetting.default_categories_selected (PR #8138)

Added on Aug 21, 2015 in bef80633b1b58189a732a3959d3a59da44aa55e9 The only usage removed on Aug 26, 2015 in 4ba89eec2799390feea4fae5ae5032013106f092

As far I can tell it isn’t used by core or any official plugins.

GitHub

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I am all for removing dead code.

sure lets kill it and see what happens! :+1: