Fix order of NB callbacks (and a crash)

[idryzhov]

lib: add missing priority for affinity map callbacks

Other objects depend on affinity-maps being created before them by using
leafref with require-instance true. Set the priority to ensure that.

lib: fix order of northbound callbacks

When ordering the NB callbacks according to their priorities, if the
operation is "destroy" we should reverse the order, to destroy the
dependants before the dependencies.

This fixes the crash, that can be reproduced with the following steps:

frr# conf term file-lock
frr(config)# affinity-map map bit-position 10
frr(config)# interface test
frr(config-if)# link-params
frr(config-link-params)# affinity map
frr(config-link-params)# exit
frr(config-if)# exit
frr(config)# mgmt commit apply
frr(config)# no affinity-map map
frr(config)# interface test
frr(config-if)# link-params
frr(config-link-params)# no affinity map
frr(config-link-params)# exit
frr(config-if)# exit
frr(config)# mgmt commit apply

[idryzhov]

@Mergifyio backport dev/10.0

[mergify]

backport dev/10.0

✅ Backports have been created

• #15403 Fix order of NB callbacks (and a crash) (backport #15401) has been created for branch dev/10.0