Longer test files for longer CI jobs are missing

The scripts/testv/ directory contains only short test files that are currenlty used only for self_test.py. However, longer test files that could be used e.g. for thorough CI jobs using scripts/config/ci_linux.json are missing. The task is to create longer test files, ideally from meaningful signals uploaded at https://forge.3gpp.org/rep/ivas-codec-pc/ivas-pc-testfiles/-/tree/main/testv