[BUGFIX] Typo3DatabaseBackend get function does not return FALSE

Typo3DatabaseBackend get function does not return FALSE when
there is no result.

Change-Id: I738ffc2879a9c125af4e7f0727c2cb5c88ed2da0
Fixes: #46802
Releases: 6.1
Reviewed-on: https://review.typo3.org/19445
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert