chore: fix kokoro config for samples (#236)

Source-Link: https://github.com/googleapis/synthtool/commit/dd05f9d12f134871c9e45282349c9856fbebecdd
Post-Processor: gcr.io/repo-automation-bots/owlbot-python:latest@sha256:aea14a583128771ae8aefa364e1652f3c56070168ef31beb203534222d842b8b
5 files changed