fdo#79303: Revert "fdo#70861 SwToSfxPageDescAttr: fix call to ...

... SvxExtParagraphTabPage"

This reverts commit 5ce19ddcb6595c71980aecfa1e8c0827343159a4.

It is now simply wrong to claim that a SID_ATTR_PARA_PAGENUM item with
value 0 is set, when that is a valid offset value.

SwTxtShell::Execute() will call SfxToSwPageDescAttr() which pulls the
SID_ATTR_PARA_PAGENUM out of the item set and sets it.

Change-Id: If5a155c2874486b3ef7d01883fe73f8e5fca46fe
fdo#70861: cui: fix crash in SvxExtParagraphTabPage

SvxExtParagraphTabPage::Reset() must not request a pool default for
SID_ATTR_PARA_PAGENUM because it simply does not exist; the item is
backed by a member of SwPageDesc in Writer.

Change-Id: I9b157f048cd986566f9b01f3677b53d5974b6c8d
svl: deploy some asserts in SfxItemPool, those are bugs

Change-Id: Ifa28f3b02640720855a6e40ddd7a5f752904e8bd