Build Python 3.6 agent in Kokoro script.
Build Python 3.6 agent in Kokoro script.

Also stop copying distutils and setuptools since they are installed already.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=186682723

GoogleCloudPlatform/cloud-debug-python,GoogleCloudPlatform/cloud-debug-python,GoogleCloudPlatform/cloud-debug-python