Guacamole Linux VM `vm_config.sh` fails and prevents guacamole connections

Guacamole Linux VM vm_config.sh fails when pulling apt packages - see log below.

Appears to be caused by the Nexus package config still pinned to bionic:

https://github.com/microsoft/AzureTRE/blob/464decc42836c35c18eaa32d949ff52a368c76e6/templates/shared_services/sonatype-nexus-vm/scripts/nexus_repos_config/ubuntu_proxy_conf.json#L30-L33

Enable succeeded: 
[stdout]
amd64 Packages [456 kB]
Get:10 https://XXX.francecentral.cloudapp.azure.com/repository/microsoft-apt/ubuntu/22.04/prod jammy/main all Packages [1319 B]
Get:11 https://XXX.francecentral.cloudapp.azure.com/repository/microsoft-apt/repos/edge stable/main amd64 Packages [43.0 kB]
Get:12 https://XXX.francecentral.cloudapp.azure.com/repository/microsoft-apt/repos/vscode stable/main amd64 Packages [34.9 kB]
Get:13 https://XXX.francecentral.cloudapp.azure.com/repository/microsoft-apt/repos/azure-cli jammy/main amd64 Packages [3388 B]
Get:14 https://XXX.francecentral.cloudapp.azure.com/repository/microsoft-apt/repos/azure-cli jammy/main all Packages [1093 B]
Ign:1 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu jammy InRelease
Ign:2 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu jammy-updates InRelease
Ign:3 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu-security jammy InRelease
Get:15 https://XXX.francecentral.cloudapp.azure.com/repository/docker jammy/stable amd64 Packages [83.5 kB]
Ign:1 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu jammy InRelease
Ign:2 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu jammy-updates InRelease
Ign:3 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu-security jammy InRelease
Err:1 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu jammy InRelease
  502  Bad Gateway [IP: X.X.X.X 443]
Err:2 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu jammy-updates InRelease
  502  Bad Gateway [IP: X.X.X.X 443]
Err:3 https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu-security jammy InRelease
  502  Bad Gateway [IP: X.X.X.X 443]
Fetched 686 kB in 9s (75.6 kB/s)
Reading package lists...
Building dependency tree...
Reading state information...
All packages are up to date.
W: Failed to fetch https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu/dists/jammy/InRelease  502  Bad Gateway [IP: X.X.X.X 443]
W: Failed to fetch https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu/dists/jammy-updates/InRelease  502  Bad Gateway [IP: X.X.X.X 443]
W: Failed to fetch https://XXX.francecentral.cloudapp.azure.com/repository/ubuntu-security/dists/jammy/InRelease  502  Bad Gateway [IP: X.X.X.X 443]
W: Some index files failed to download. They have been ignored, or old ones used instead.

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Reading package lists...
Building dependency tree...
Reading state information...
Calculating upgrade...
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Reading package lists...
Building dependency tree...
Reading state information...
Package gnupg2 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  gpgv gpgsm gnupg-l10n gnupg dirmngr

Package debconf-utils is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  debconf-i18n

E: Package 'gnupg2' has no installation candidate
E: Unable to locate package gdebi-core
E: Package 'debconf-utils' has no installation candidate
2026-07-23 09:05:10,576 - cc_scripts_user.py[WARNING]: Failed to run module scripts_user (scripts in /var/lib/cloud/instance/scripts)
2026-07-23 09:05:10,576 - log_util.py[WARNING]: Running module scripts_user (<module 'cloudinit.config.cc_scripts_user' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_scripts_user.py'>) failed
Cloud-init v. 26.1-0ubuntu1~22.04.1 finished at Thu, 23 Jul 2026 09:05:10 +0000. Datasource DataSourceAzure [seed=/dev/sr0].  Up 62.48 seconds

[stderr]