I'm exactly in the same situation as you: 3 given names and one full name.
I don't think I've ever put anything put my first name and last name in flight bookings, and I've never had an issue with this.
This is pretty common, and as far as I know most procedures and systems are designed to handle this. Many airline ticketing systems just don't have the space for all given names anyway. Likewise the MRZ on many forms of ID has limits on how long the full name can be and are designed to deal with truncation.
If the destination/transit countries require a visa, ETA, ESTA, e-Visitor or anything else like that, however, you should provide your full name in those applications.
If the destination/overflown countries require API (Advance Passenger Information), you should provide your full name on that form. Sometimes airlines block input into the first and last name fields and re-use those from your booking, which may lead to issues automatically matching to an ESTA/ETA/e-Visitor. Worst case, they will scan the passport at check-in and use what is on your passport.