keycloak_quarkus: v26.4.x compatibility

[hwo-wd]

closes #314

[RanabirChakraborty]

@hwo-wd are you still working on this PR?

[hwo-wd]

Not actively, no since I consider it done, actually.
Using this branch, I've deployed RHBK 26.4.6 to test, dev and pre-prod, where I'm facing a regression which is preventing me from upgrading the actual production (nothing too serious, Case #04330104);
but from the role perspective I'd be happy to take your feedback and I'd say we can get it merged, I just don't know why the molecule tests aren't working though

[RanabirChakraborty]

Molecule tests are passing, just need to do the little changes. Other than that it's good.