Install python2 in the Dockerfile.
Install python2 in the Dockerfile.

Without it, we get a build failure (inside the container) when trying to build
//runsc.

PiperOrigin-RevId: 286474518

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