Commit f3ce30ec changed this to return
after first non-throwing XNameContainer::hasByName, regardless if it
returned true or false.

This changes it back, to iterate over all the providers again.

Change-Id: I74fa4d4aa8760cad509442226601ab4842312b80
Reviewed-on: https://gerrit.libreoffice.org/65471
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>