Wrong FlashMessage queue for BE requests

Hello,

setting the flashmessage queue to "extbase" is OK for FE requests, but, if I save a record in BE I don't get any flashmessages regarding non-found and related POIs.

https://github.com/jweiland-net/maps2/commit/0fbfe1c38c189b58eb3145b9df0ffbfe98df9ad2#diff-0cbd17bfab0e88b1a6c64335d9613bfe12b0737bf8ea804dc97f2d50779ca2d7R169

Stefan