API: tools: Drop cibadmin --extended-version/-! option

It has been hidden since it was introduced in bc5de9a8. It was
internally marked as deprecated in 1f69abe5. There are no known internal
or external users of this option. pacemakerd --features gives similar
output, with the addition of the CRM_FEATURE_SET.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>