CCM-15019: remove data-plane from the new event after a rebase

Author: nhsd-angel-pastor

src/cloudevents/domains/digital-letters/2025-10-draft/events/uk.nhs.notify.digital.letters.print.invalid.attachment.received.v1.schema.yaml

@@ -10,7 +10,7 @@ properties:
     description: Concrete versioned event type string for this event (.vN suffix).
   source:
     type: string
-    pattern: ^/nhs/england/notify/(production|staging|development|uat)/(primary|secondary|dev-[0-9]+)/data-plane/digitalletters/print
+    pattern: ^/nhs/england/notify/(production|staging|development|uat)/(primary|secondary|dev-[0-9]+)/digitalletters/print
     description: Event source for digital letters.
   dataschema:
     type: string