Remove QHeaderView::setDefaultSectionSize calls

Do not set the row height in pixels, since that
will break in High DPI situations. We do that for
some QTableViews, apparently as an obsolete
workaround.

QTableView does the right thing by default,
therefore we don't need to set that value at all.

Task-Number: QTCREATORBUG-11179
Change-Id: Id90f01316f8359207796a4060cb43b0aba93d441
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>