[BUGFIX] Correct table icon in EXT:test_select_flex_mm

iconfile target should be Extension.svg
instead of Extension.gif

Resolves: #97906
Releases: main
Change-Id: Icf0bc949982d635644c1a59c5c278d726c165825
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75124


Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>