[BUG] Open basedir restrictions for extension js/css in backend

[naturefund-falk]

Describe the bug
In my error log i get the following entries for backend requests
Core: Error handler (BE): PHP Warning: file_exists(): open_basedir restriction in effect. File(/typo3conf/ext/solr/Resources/Public/JavaScript/SearchStatistics.js) is not within the allowed path(s) ... GeneralUtility.php line 2317 Core: Error handler (BE): PHP Warning: file_exists(): open_basedir restriction in effect. File(/typo3conf/ext/solr/Resources/Public/StyleSheets/Backend/InfoModule.css) is not within the allowed path(s) ... GeneralUtility.php line 2317

To Reproduce
Steps to reproduce the behavior:
Go to the info module of the solr extension

Expected behavior
I expect no error messages of this kind

Used versions (please complete the following information):

• TYPO3 Version: 11.5 (composer installation)
• EXT:solr Version: 11.5.6
• PHP Version: 8.1

Additional context
It looks like the js/css files are somehow included the wrong way or with a wrong path. The /typo3conf should be prefixed with the typo3 system path or it should be no absolute path.

[dkd-kaehm]

@naturefund-falk
Thanks for reporting that issue.
That is not fully resolved: #3897.
We want the similar solution as in b49c09d for all files and resource inclusions within Resources/Private/Templates/Backend path.

Could you create a pull-request against release-12.0.x branch?