Replace dark theme's $authpage-primary-color
Replace dark theme's $authpage-primary-color

Use `$primary-content` instead of `$text-primary-color`.

Signed-off-by: Andrew Ferrazzutti <187770cf5af2d3469ab41bc3cb1a5c052fc2099f@miscworks.net>

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk