[BUGFIX] Do not use returnUrl and index.php for workspace logout links

When a workspace preview is given, previously
a URL to "index.php" was set, which is not needed anymore.

Instead, the logout link for workspace preview links
should link to the current URL but only with ADMCMD_prev=LOGOUT.

The patch changes the implementation to use UriInterface
instead of string magic.

Resolves: #92398
Releases: master, 10.4
Change-Id: I3fffe5e43689b41c6f0423c53459e39e230e6278
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65847


Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Claus-Peter Eberwein <claus-peter.eberwein@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Claus-Peter Eberwein <claus-peter.eberwein@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>