Set a minimum number of days for automatic deactivation

Problem to solve

Follow up to this MR - !95496 (merged)

Because deactivated users can rectivate simply by logging in, setting a low threshold could result in unexpected re-activations, and combined with additional users being added, result in seat overages.

Proposal

The number of days field should be a text field instead of a drop down.

Accepted number of days should be 90 days and over.