Refactor kokoro/run_tests.sh
Refactor kokoro/run_tests.sh

This will make it easier to add RBE to bazel.

PiperOrigin-RevId: 225865250
Change-Id: I530b5e09875267c18dc6e7e16590fe9e128253ac

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