Diskimage retrofit on Victoria does not include required script

[Alex Zero]

The Victoria release of Octavia requires the /usr/local/bin/udp-masquerade.sh script to be present. This charm has not been updated to include it in the retrofitted image, which results in VIPs failing to be provisioned.

2021-01-23 21:07:23.983 3807713 ERROR octavia.amphorae.drivers.haproxy.exceptions [-] Amphora agent returned unexpected result code 500 with response {'message': 'Error plugging VIP', 'details': 'Waiting for DAD... Done\n/bin/sh: 1: /usr/local/bin/udp-masquerade.sh: not found\nifup: failed to bring up eth1:0\n'}