[CI] enable timeout in pyivastest scripts
Pure CI change.
Enable the pyivastest scripts to set a timeout for each subprocess encoder/decoder run. This causes the run to fail if the timeout is exceeded and report that properly. In case of an endless loop in the codec, this adds proper reporting of the issue instead of a timeout in the CI job, e.g.: https://forge.3gpp.org/rep/ivas-codec-pc/ivas-codec/-/jobs/210313.