Issue #3612441: Fix functional and unit tests for Drupal 11.4 (3.0.x backport)

Backport of the Drupal 11.4 test fixes to 3.0.x (see the 4.x MR !407 (merged)).

Test-only: create Page/Article content types when the Standard profile omits them, re-confirm the domain fields, assert on the per-view-mode Manage display path, and initialise the container before constructing the route provider. All changes are no-ops on cores where the Standard profile still ships those content types.