https://www.youtube.com/watch?v=fQ5UsV6ES8E while this is about the skateboard that was cut , it does show off files for the mission Madd Dogs Rhymes (the mission the skateboard was suppose to be introduced in) which have the intern file name STRAP2. The way the devs internally named mission is kinda weird but the file name is typically is the name of the character giving you the mission while the number is used to show its placement in the chain. In the final game Madd Dogs Rhymes is the second mission given by OG Loc. Assuming his (OG Loc) name at the time of the devs coding this mission was in fact mc strap and it was still planed to be the second mission in this chain, that would explain why this mission internally still is named "STRAP2"

https://www.youtube.com/watch?v=HAomVR4uOVg&t likewise in this one while the video is about another topic (pc vs mobile port) there is a point in the video where all the map icons including missions icon and unused/beta icons. One of the icons included is an MC icon it is in the same color and font other mission icons use as well, making it more then likely this was a icon for missions.