fdo#74524: ODF import: fix unhandled exception in annotation import cp#1000075

Crash with unhandled UnknownPropertyException when trying to get "Name"
property from a PageNumber field.

(cherry picked from commit cf26d7614364176742ae0303efb4499a37ae04c8)

Change-Id: I501cc138caba034c85630519014b94d783ab8f39