Fixes random stuff that is broken on bazel/kokoro.
- random output coming back as "bytes" object instead of str
- missed syntax error in bazel
- a flag is missing in the version of gcloud on kokoro
PiperOrigin-RevId: 301915289
This formalizes the adhoc scripts previously in kokoro. The image targets can
be used by e.g. benchmarks in order to automated image prepation.
PiperOrigin-RevId: 290982744