Fix duplication of '[PYTHON_BINARY, CLCACHE_SCRIPT]' in integration tests
Fix duplication of '[PYTHON_BINARY, CLCACHE_SCRIPT]' in integration tests

This not only saves some code, it also prepares a change in which I
implement an alternative way to run clcache (via Coverage.py).

webmaster128/clcache,webmaster128/clcache,webmaster128/clcache