[BUGFIX] Prevent 'Undefined array key' in FileDeletionAspect

Properly check for valid meta data record
to prevent 'Undefined array key' error on
deleting a file.

Meta data record might not exists, because
the file might have not been indexed or
simply because the record was manually deleted.

Additionally, some code clean up is done.

Resolves: #102700
Releases: main, 12.4
Change-Id: Ibf8a0d53b40f08b60064583d5f28762c25d75937
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82262


Tested-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Jörg Bösche <typo3@joergboesche.de>