Breaking: #57382 - Remove old flash message API 

See forge#57382

Description 

The old flash message API is removed.

Impact 

Extensions relying on the old (static) flash message queue API will not work anymore. Extbase removes the protected old flashMessageContainer.

Affected installations 

Any installation that uses an extension relying on the old API.

Migration 

Change the API calls to not be of static kind anymore. Extbase extensions have to use getFlashMessageQueue() of the controllerContext