Point the Kokoro test script to the actual location of install.sh.
Point the Kokoro test script to the actual location of install.sh.

PiperOrigin-RevId: 204501071
Change-Id: Ia5f7ca725bf68ee53ff3922b13c75c0685467ce9

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor