Disabling Guacamole Login

[cptanalatriste]

✅ Checklist

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🚦 Depends on

⤴️ Summary

To ensure users use OpenID for authenticating in the SRE, Guacamole requires the extension-priority setting to have the value openid (see: https://guacamole.apache.org/doc/gug/openid-auth.html). In Docker, this setting is exposed via the EXTENSION_PRIORITY environment variable (see: https://guacamole.apache.org/doc/1.5.3/gug/guacamole-docker.html).

🌂 Related issues

Closes: #2467

🔬 Tests

Tested on a Tier-0 SRE.

[jemrobinson]

LGTM

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.