libyang: bug when uses clause references a leaf-list

[bradh352]

There is a bug in libyang when attempting to validate table BGP_PEER_GROUP_AF and likely BGP_NEIGHBOR_AF in respect to route_map_in and route_map_out.

The issue is with the use of leaf-list specifically when it is pulled in via a uses clause of bgpcmn:sonic-bgp-cmn-af.

The error message resembles that of if a child is specified that isn't recognized at all:

All Keys are not parsed in BGP_PEER_GROUP_AF
dict_keys(['default|PEERS|ipv4_unicast'])
exceptionList:["'route_map_in'"]

Moving the leaf-list to the parent rather than being imported through the uses clause works around this issue.

This issue is "worked around" in PR #21078 and should be reverted once the issue is fixed in libyang (which may be as simple as upgrading the libyang version in use).