Remove ignoreErrors setting when support for v11 is dropped

[christianbltr]

Once support for TYPO3 11 is dropped these lines should be removed from Tests/phpstan.neon

	reportUnmatchedIgnoredErrors: false

		- '#PHPDoc tag @var for variable \$moduleData contains unknown class TYPO3\\CMS\\Backend\\Module\\ModuleData\.#'
		- '#Call to method get\(\) on an unknown class TYPO3\\CMS\\Backend\\Module\\ModuleData\.#'
		- '#Call to an undefined method TYPO3\\CMS\\Backend\\Template\\ModuleTemplate::assign\(\)\.#'
		- '#Call to an undefined method TYPO3\\CMS\\Backend\\Template\\ModuleTemplate::renderResponse\(\)\.#'
		- '#Class TYPO3\\CMS\\Backend\\View\\BackendViewFactory not found\.#'
		- '#Access to constant ERROR on an unknown class TYPO3\\CMS\\Core\\Type\\ContextualFeedbackSeverity\.#'