Adapt the test job artifacts archiving script to their new location

In the #10151 (closed) related branch, the screenshots, video captures and pcap files of a test suite run will be stored in a sub-directory of TMP_DIR.

In the Jenkins environment, the post_test_cleanup script copy them back in the workspace so that Jenkins can archive them. It uses a find "${TEMP_DIR}" -maxdepth 1 [...] to do so, which won’t work anymore.

So once #10151 (closed) is merged, this find will have to be modified accordingly, likely by removing the -maxdepth 1.

Parent Task: #10153 (closed)

Original created by @bertagaz on 10356 (Redmine)