fdo#71248 Excel VBA: ActiveDocument is not tracking currently selected Doc

Change-Id: I86606646206ec26e2822a6e27888537d44351b7b
Reviewed-on: https://gerrit.libreoffice.org/11725
Reviewed-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
Tested-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
(cherry picked from commit 4108bd9b7a41eaa0f3bf8b8173f27f57e009ee34)
Reviewed-on: https://gerrit.libreoffice.org/11827
Reviewed-by: Muthu Subramanian K <muthusuba@gmail.com>