[TASK] Remove PHP < 7.4 from build plans

With upcoming TYPO3 v11, support for PHP versions older than 7.4 is
cancelled. Due to this, we don't have to check these versions anymore in
Bamboo and thus remove them from the build plans.

Resolves: #92888
Releases: master
Change-Id: Iae261d4f4bc8ec205a583f685fda2ef183f32767
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66714


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>