chore: update keycloak to version 26

[shreddedbacon]

General Checklist

• Affected Issues have been mentioned in the Closing issues section
• Documentation has been written/updated
• PR title is ready for inclusion in changelog

Database Migrations

• If your PR contains a database migation, it MUST be the latest in date order alphabetically

Description

Update keycloak to v26.0.7

Supporting pullrequests:

• chore: import keycloak-js lagoon-ui#307
  • changes the ui to use keycloak-js directly as the provided keycloak.js client in keycloak has been removed
• chore: support for keycloak 26 lagoon-charts#733
• feat: support insecure tls connections if required lagoon-ssh-portal#497
  • with the enforcement of https on keycloak, ssh-portal fails to verify the issuer due to self signed certificate and crashes

[shreddedbacon]

Starting a k3d cluster and installing a stable chart version (latest stable chart) using, using LAGOON_CORE_USE_HTTPS=false to ensure that no certificates are used (as the default will be true in the future)

make k3d/stable-local-stack LAGOON_CORE_USE_HTTPS=false

Then running the upgrade using the following to install the changes in this repo and the associated CHARTS_TREEISH branch, we can observe the upgrade of a stable version of lagoon-core/lagoon-remote to the one in CHARTS_TREEISH.

make k3d/install-lagoon

I also checked that going to Keycloak 26.1.0 was possible, I haven't changed this at this stage to do so, but it should be possible if we want to risk going to it, rather than wait for a .1 or other.