[BUGFIX] Remove double escaping in warning in DatabaseRecordList

As the flash message's title and text are escaped already, remove the
htmlspecialchars in DatabaseRecordList.

Additionally remove the text "Warning:" from the text as this is already
expressed by the flash message itself.

Resolves: #81494
Releases: master, 8.7
Change-Id: I557dfb6f1422d2194dcdf83bbbc156a99efb290e
Reviewed-on: https://review.typo3.org/53146


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Josef Glatz <josef.glatz@typo3.org>
Tested-by: Josef Glatz <josef.glatz@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>