Responsive alignment classes shouldn't hardcode grid tiers

Created by: cvrebert

https://github.com/twbs/bootstrap/blob/807fb8847aa8cbe54ad371fccdec93b2518c1558/scss/_utilities.scss#L63-L89 should be refactored to use a loop over $grid-breakpoints instead of hardcoding each of the breakpoints. (Found while investigating #18026 (closed).)