CustomAnimationCreateDialog: select previously set misc animation

Regression from 9695f38ca4ab26b40524f2eade98c45f0360131d.

Change-Id: I8777fd8fa3e31c67b6645044d262fd4c5f645634
(cherry picked from commit dd1f8ac3575a929e71b39d5f7043be057ebaa727)
Reviewed-on: https://gerrit.libreoffice.org/9480
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>