[BUGFIX] Re-determine first start module if configuration is invalid

This patch fixes two flaws with the determination and loading of the
first available backend module:

* ModuleLoader::getModuleSetupInformation() only sets default options if
  the configuration array is not empty
* The availability of the module is checked. If the configured module
  doesn't exist, the first available module is determined again.

Resolves: #91210
Releases: master
Change-Id: Idae8de6e0bf253754c4d44e50b15e81038e1315f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64309


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Daniel Siepmann <coding@daniel-siepmann.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Daniel Siepmann <coding@daniel-siepmann.de>
Reviewed-by: Josef Glatz <josefglatz@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>