Thats simple. All you need to do is open the console and type in "sv_idlebots 1" without the quotation marks, and any bots you have in the game or you add to the game will not move round.
You can also get there from the ingame bot settings menu from the same menu you use to add new bots. Additionally you can set them to be free to move, but just ignore human players. Meaning they will still move round and fight amongst themselves, but they will not attack you or any other human player in your server.