network: dhcp4: do not assign new address before old one is not removed

If DHCP4 client lost a lease, and then soon acquire new lease, then
the removal of the old address may not be completed. If that happens,
and the new and old addresses are the same, then the new address will be
considered as a foreign address. Such a situation can occur when the
DHCP4 server is restarted.

This makes networkd wait for the removal of the old address when a new
lease is acquired.

This also makes the link in configuring state when renewing address.