I know exactly what you mean as when I'm running long I also twitch my fingers a certain way. Doesn't give me tendonitis but I can see what you're getting at. It's like people who sit with one leg crossed over the other wiggling their ankle back and forth without realising they're doing it. Or autistic people rocking or hand flapping.
Rather than wondering about whether to wear gloves or mittens, I think you'd get on better with practicing mindfulness and learning how to not twiddle your fingers when your mind drifts off while running. Smarties tubes may work well in the short term as you'll probably feel so silly with them stuck on your fingers that it might encourage you to stop twiddling a lot faster than you'd manage without them!