Fix indentation in MetaReader.read_metadata
Fix for a bug introduced by !25360 (merged) and causing CI failures in master. The CI for !25360 (merged) was successful because the issue was only uncovered by !24196 (merged) which started using MetaReader in the CI test job. Thus, only the combination of both MRs lead to failing CI.
The bug is incorrect indentation causing the loop over input files to return after the first file.