Improve interop test traceability for C# and Perl on CI

Currently, interop tests for C# and Perl don't output logs about which files were checked and which were skipped.
Adding such messages is useful for ensuring if these tests correctly work.

https://github.com/apache/avro/runs/2133175520?check_suite_focus=true#step:8:52
https://github.com/apache/avro/runs/2133175833?check_suite_focus=true#step:10:10