Set back this 20 MB default value for compatibility reasons

See also:
dbdacc73ae154237314d599194cc686bd738a9bf

This ten multiplier which was moved from the implementation
to the settings is live in the code only from 4.4 version, so
actually we can remove it without any problem, don't need to change
the default value on the UI.
I don't have any other reason to change that value so...

Change-Id: Ia17874cafeb013b89eedc300710392763c868f44
(cherry picked from commit 9d0f597cee004b4f09f87e3599a85fc2e3672ee9)
Test for linked graphic export / import of Impress

To avoid regression fixed by:
02b17c1bbdd19a978b9de646c0dacdad179c60de

It seems PPTX import is broken now.

Change-Id: I17228f4d8511b43d028b9ed8a6e77505e6143860
(cherry picked from commit 33e49c711c988dfbbb75b605878850f83180a796)
Test for linked graphic export / import of Calc

To avoid regression fixed by:
02b17c1bbdd19a978b9de646c0dacdad179c60de

Change-Id: Iaf2dea0cf221cb0e53debe4c1c611aab86dc29ff
(cherry picked from commit ff8f2cb8ebde75cce65bb715fefcad778d568fe4)
Test for linked graphic export / import of Writer

Change-Id: Ib41921e9ceed30a05e16ace298d9c5dc87cc5458
(cherry picked from commit 3f28f67084f12fd806e05020ed8bac8d5a05c025)