sig#779 - Upgrade to Keycloak version 25

[evegufy]

Description

Upgrade centralidp and sharedidp to Keycloak version 25.
The latest version at this point in time is 25.0.6 (corresponding to Bitnami chart version 23.0.0)

Important: the Postgres version of the dependency needs to remain 15 (as that's the aligned version in TRG 5.07) and the Bitnami chart has already moved on to Postgres version 16 in the subchart.

Acceptance Criteria

• App version has been upgraded to v25
• Postgres version of the dependency is still 15

Benefits

Keeping up to date with the latest Keycloak releases offers several benefits like security patches and bug fixes as well as new features, see release notes v24 and release notes v25.

[evegufy]

Upgrade to v25 done.
I was also considering directly upgrading to v26 but as that version was out only very recently at that point and I encountered some issues which would impact our current sandboxes (Umbrella and LocalDev) due to further security enhancements essentially not supporting cross-origin POST requests - so a regular browser flow - when running in an insecure context (without TLS, with the exception of localhost), I postponed it.
Relates to:
keycloak/keycloak#32087
keycloak/keycloak#32130
https://keycloak.discourse.group/t/error-web-crypto-api-is-not-available/28381