Remove deprecated code around sessions for the major release #43260

Description

Several interfaces and methods have been deprecated during KC 26.x and can now be removed for KC 27.0

We'll have a focus on session handling

Discussion

Remove the following methods that are deprecated in 26.4 or earlier:

We'll double check with the core-clients team if it is ok if we update the AuthenticationSession* items, or if the core-clients team.

• org.keycloak.models.sessions.infinispan.stream.Mappers#toStream
• AuthenticatedClientSessionModel#getCurrentRefreshToken*
• AuthenticationSessionProvider#removeAllExpired, removeExpired
• AuthenticationSessionProvider#updateNonlocalSessionAuthNotes
• AuthenticatedClientSessionModel#getTimestamp / setTimestamp
• UserSessionProvider#getKeycloakSession / getClientSession / createUserSession / importUserSessions
• org.keycloak.**.infinispan.**#** (in module "keycloak-model-infinispan")
• UserSessionPersisterProvider.loadUserSessionsStream(Integer firstResult, Integer maxResults, boolean offline, String lastUserSessionId)
• Background task to batch persistent session updates

Create multiple sub-tasks as needed to keep changes isolated.

Motivation

• Clean up the code, thereby making it simpler to maintain.
• Remove items that have been deprecated in KC 26.4, as this was the last published for RHBK release.
• Items in private modules can be removed even if they are not deprecated after careful consideration.
• This also opens the door for simplifications that can improve the performance.

Details

No response