[TASK] Set default minimum logging severity to warning

The TYPO3 default context is production. Therefore the default
logging should be limited to warnings and more severe levels.

Releases: master
Resolves: #67216
Change-Id: Ia4b34e67f99d475630f3401d459a1415146eb661
Reviewed-on: http://review.typo3.org/39839


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>