fdo#68160 Revert "Resolves: #ii122335# Disabling the old task pane"

fdo#68160 Revert "Partly revert "Resolves: #ii122335# Disabling the old task pane""

This reverts commit cb4225144f1fff44f9bb972fe06f51524da11b8b.

To be able to revert 95ae39c0c34c9a5e6fa6e72bf3a631a9a799b872 entirely.

fdo#68160 Revert "Resolves: #ii122335# Disabling the old task pane"

This reverts commit 95ae39c0c34c9a5e6fa6e72bf3a631a9a799b872.

We need a TaskPane even in Writer and Calc to be used by extensions.
Sidebar is experimental so TaskPane is needed anyway for Impress (see
fdo#72371).

Change-Id: Ia94ab377a59996ba434b56e3823117183674afb7
Reviewed-on: https://gerrit.libreoffice.org/7042
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>