Remove extraneous solution element from square_roots_2

What in the world?!?

Test plan: local/chrome

fix #42567; fix #42552; fix #42539; fix #42517; fix #42516; fix #42515;
fix #42506; fix #42504; fix #42483; fix #42428; fix #42425; fix #42424;
fix #42421; fix #42409; fix #42406

Auditors: alpert