[BUGFIX] Handle FileDoesNotExistException in `cleanup:missingrelations`

It's possible that file references to files exists, where
the physical file is missing. That stopped further file
reference processing in the ext:lowlevel cleanup command
`cleanup:missingrelations`.

Therefore, this change explicitly catches the concrete
`\TYPO3\CMS\Core\Resource\Exception\FileDoesNotExistException`
exception and outputs the message, without interrupting the
processing of further files.

The handling code is moved to a dedicated method to clean
up code duplication on the same step as a side-change.

Other unforeseen errors still stop the execution.

Resolves: #101924
Releases: main, 12.4
Change-Id: I2c8dba34a6f99d891408b5cc8fd86bddcb3c90c2
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81024


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Stefan Bürk <stefan@buerk.tech>
R...