[BUGFIX] Fix link for workspace preview

The absolute link generated for mailings to
workspace editors misses the page id.

The uid has been accidentally removed with
commit for #56359

Resolves: #56375
Releases: 6.2
Change-Id: I521aee2b96c542c27a911ffeab5d9bfffc8b9a46
Reviewed-on: https://review.typo3.org/27893
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel