Slow drones won't be able to engage an F-35 in A2A combat because that's primarily determined by energy state. A Cessna 172 can carry about 100lbs of weapons after taking fuel and pilot into consideration. A Stinger weighs about 30 lbs or so, so three could be carried. Range of the Stinger is about 5 miles, so still sounds plausible.
So your cloud of Cessnas could conceivably carry 60 Stingers. How will they detect a fighter flying at 30K? A 172 can only get to about 15K in perfect conditions. It flies at like 100mph compared to a Mach 2 F-35.
Again, short of being a suicide bomber trying to kill an F-35 on the ramp, this idea is ludicrous.