It's not available as an option on Jive for Teams, although Image size is. I have previously indicated the inconsistency.
You might try asking Support to alter it for you, they did for me, but that was when they had more latitude - they may not do it now. Failing that ping Olivia Teich who previously asked what 'ideal' settings would be .
Edit: I made this public: Attachment Control
Edit 2: See Re: Full Sys Admin Access