This modifies commit a6f2199e
"DOCX import: don't try to set grab-gag props as UNO props"

Perhaps that commit should simply be reverted, but I will trust
that the commit was mostly OK and simply adjust the logic so
that *InteropGrabBag is ignored as before.

Doing this resolves MSO being unable to open a specific document
and LO missing some numbering during LO round-tripping.
Probably these are just side-effects from other locations in the
code that couldn't deal with these unexpected properties. For
example, the numbering.xml file is malformed, since it is
missing the w14: namespace.

Unfortunately, I failed in my attempt to create a minimal
test document.

Change-Id: Idf88cd09d96546b7f03d326afb5f6e58439bcf20
Reviewed-on: https://gerrit.libreoffice.org/53271Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Justin Luth <justin_luth@sil.org>