Replace link with button in devise shared links

Cf. conversation https://github.com/consuldemocracy/consuldemocracy/pull/5955#discussion_r2158715957
Need to get this i18n_spec.rb to run to delete the key
shared.links.signin_with_provider.

config/locales/en/devise_views.yml

@@ -69,7 +69,6 @@ en:
         new_confirmation: Haven't received instructions to activate your account?
         new_password: Forgotten your password?
         new_unlock: Haven't received unlocking instructions?
-        signin_with_provider: Sign in with %{provider}
         signup: Don't have an account? %{signup_link}
         signup_link: Sign up
     unlocks:

config/locales/es/devise_views.yml

@@ -69,7 +69,6 @@ es:
         new_confirmation: '¿No has recibido instrucciones para confirmar tu cuenta?'
         new_password: '¿Olvidaste tu contraseña?'
         new_unlock: '¿No has recibido instrucciones para desbloquear?'
-        signin_with_provider: Entrar con %{provider}
         signup: '¿No tienes una cuenta? %{signup_link}'
         signup_link: Regístrate
     unlocks: