After disabling 2FA via setupUserTwoFactorAuthentication, the API may
return is2faenabled as null or undefined rather than boolean false.
The strict equality check (=== false) prevented the "Setup 2FA" button
from appearing in those cases, making it impossible to re-enable 2FA.
Change the check to a falsy check (!record.is2faenabled) so the button
is shown whenever 2FA is not enabled, regardless of whether the value
is false, null, or undefined.
Fixes: https://github.com/apache/cloudstack/issues/13233