Update work-item references after orchestra moves WorkItem to core

Follows orchestra #3610809 (merged), which moved the WorkItem entity and its manager from orchestra_inbox into orchestra core and unified pull operations with push tasks.

• BookingWorkflowE2eTest: Drupal\orchestra_inbox\WorkItemInterface -> Drupal\orchestra; service orchestra_inbox.manager -> orchestra.work_item_manager.
• Auto-confirm assertion updated: after confirming, the flow forks into the deposit window and the operator-cancellation window; that window is a pull operation, so it now mints an operation-mode work item (previously operations had none). The test asserts the operation-mode item exists rather than asserting none.

The kernel tests that enable orchestra_inbox and install orchestra_work_item need no change (the module still exists, the entity id is unchanged and now core-provided). Verified locally against orchestra 1.x: kernel + this E2E green.