Disable autocompletion in password fields by default

See https://developer.mozilla.org/en-US/docs/Web/Security/Securing_your_site/Turning_off_form_autocompletion.

We had a head-scratcher on one site recently where a password field on a submenu page kept being changed because a user's in-browser password manager kept autofilling it whenever the submenu was opened. Is there ever a case where that behavior would be desirable by default?