Use .runner_config instead of .config Part 2

CTS TF started to read subdir .config file converted from AT.xml in the new suite impl.
This conflicts with our runner config's file extension.

Test: run vts-selftest
Bug: 78287777
Change-Id: Ic630d8057bbdaf0b409e82c3c4e99cc6ee0db4af
2 files changed