Tag the OTP field with autocomplete for password managers (#19946)

This is modeled on #19833, and based on the attribute values documented
in https://developer.apple.com/documentation/security/password_autofill/enabling_password_autofill_on_an_html_input_element?language=objc

app/views/auth/sessions/two_factor/_otp_authentication_form.html.haml

@@ -5,7 +5,7 @@
   %p.hint.authentication-hint= t('simple_form.hints.sessions.otp')
 
   .fields-group
-    = f.input :otp_attempt, type: :number, wrapper: :with_label, label: t('simple_form.labels.defaults.otp_attempt'), input_html: { 'aria-label' => t('simple_form.labels.defaults.otp_attempt'), :autocomplete => 'off' }, autofocus: true
+    = f.input :otp_attempt, type: :number, wrapper: :with_label, label: t('simple_form.labels.defaults.otp_attempt'), input_html: { 'aria-label' => t('simple_form.labels.defaults.otp_attempt'), :autocomplete => 'one-time-code' }, autofocus: true
 
   .actions
     = f.button :button, t('auth.login'), type: :submit