[C2] Registration process duplicates terms validation

[ywarnier]

When terms and conditions are enabled and the terms appear at the bottom of the registration form, a checkbox appears to confirm I agree to the terms, but when selecting it and clicking "Validate", the form changes and asks me to validate again, with the additional text "You confirm that you really want to subscribe to this platform.".

I think the message in blue is from previous versions and should not be there anymore.

When I first load the registration form, the button should just say "Register" and I should only need to click it once.

[christianbeeznest]

It is checked with this commit 74183da

Thanks for confirmation.