m_sCurrentParaStyleName sounds like a nice idea, and has been
around since the initial fork, but by the time finishParagraph()
rolls around, the chances that it is still accurate are rather low.
Anything that contains a paragraph (like comments, textboxes,
shapes, tables, flys etc) might have modified that value.

This fix queries the current paragraph itself to see if
PROP_PARA_STYLE_NAME is set, which it typically is by
lcl_startParagraphGroup() except when IsInShape().
If it isn't specified, then fallback to the previous result, which
still may not be accurate, but at least it won't be a regression.

It is too late in the development cycle to look into fully
eliminating m_sCurrentParaStyleName. I hope to investigate that
in the 6.2 development cycle.

Change-Id: I124688d864f553dd5778b3593f511cc41d31c262
Reviewed-on: https://gerrit.libreoffice.org/54085Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Justin Luth <justin_luth@sil.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>