"ESRF" authentication form should be removed

Since the move to SSO, the "ESRF" authentication form no longer works and should be removed. It is confusing for users, as observed during testing with UO and stores (notably).

I suggest we move the SSO box into an "ESRF SSO" tab, in place of the "ESRF" tab. This solution allows the "DB" tab to stay where it is when enabled.

I also suggest removing the alert box explaining the move to SSO authentication, as it doesn't seem relevant anymore.

We can leave a line of this sort:

ESRF, CRG staff or long term visitors: Please log in with your ESRF account (SSO).