As you mentioned, a lot of pre-service and in-service teachers have tattoos. Some more than others. When going into an interview, I wouldn't put too much thought into it. Wear the professional attire you want, if the tattoo shows it's okay, if it doesn't that's okay too. I wouldn't recommend going out of your way to hide it because you'd want to be your true self for the interview and not be accused later of "lying" or hiding something. You want to be hired for your professional abilities, qualities and accreditations, and that should be the focus of your interview. I think most schools, if not all, have advanced a lot with tattoo culture because at the end of the day it does not implicate the way teachers teach.

I don't think it's necessary to hide the tattoo. You should be true to yourself during the interview which would entail not needing to hide items such as this to them especially if the tattoo is not offensive or inappropriate for school setting.