Revert "at least fix the crash when calling SdXImpressDocument::dispose

... for now"

This reverts commit 599473a13e3c5ba669d995c913ad415bd674a16c.

moggi says the unspecified crash happened with the tests following the
comment in chart2import.cxx:75, but the tests run fine in valgrind now.

The commit creates a memory leak in the CppunitTests as
SfxBaseModel::dispose() returns early, because mbDisposed is set.

Change-Id: I987dce6a4090784d166a4a3b2e7f9e2c0cddd289
chart2: fix temp file leak caused by missing tearDown() between tests

Change-Id: Ia4ee76743c640c0c5b92ec169e619f6c8788480e
chart2: fix temp file leaks in Chart2ExportTest

Change-Id: Id128f19dee056189a34a02156fd0bf3ac14c2454