[BUGFIX] Missing relations command: optimize SQL

Iterate over each result row instead of fetching
the whole result into PHP memory.

Resolves: #75783
Releases: master
Change-Id: Icd77e5bae1839b66bb156beeef17e7d4bb7535d7
Reviewed-on: https://review.typo3.org/47786


Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Reviewed-by: Christoph Kratz <ckr@rtp.ch>
Tested-by: Christoph Kratz <ckr@rtp.ch>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Philipp Gampe <philipp.gampe@typo3.org>
Reviewed-by: Stephan Großberndt <stephan@grossberndt.de>
Tested-by: Stephan Großberndt <stephan@grossberndt.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>