[TASK] Migrate ext:scheduler to doctrine

Resolves: #75773
Releases: master
Change-Id: I857364ef92f92e1af1ff902be5af445a775b8dbb
Reviewed-on: https://review.typo3.org/47784


Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Tested-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>