= Terms and Conditions user attribute migration

The `terms_and_conditions` user attribute was accidentally changed in 21.0.0
to uppercase. This version reverts the user attribute back to lowercase.
The value of the attribute is set when accepting Terms and Conditions page.

If any of your custom extensions relies on this attribute, you may need to
adjust your code to check both attributes `terms_and_conditions` and
`TERMS_AND_CONDITIONS`.