chore: migrate to owl bot

[generated-files-bot[bot]]

Warning: This pull request is touching the following templated files:

• .kokoro/common.cfg - .kokoro files are templated and should be updated in synthtool
• .github/generated-files-bot.yml - .github/generated-files-bot.(yml|yaml) should be updated in synthtool
• README.md - README.md is managed by synthtool. However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/master/.readme-partials.yaml
• samples/README.md - samples/README.md is managed by synthtool. However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/master/.readme-partials.yaml

[SurferJeffAtGoogle]

@bcoe Please use your admin powers to merge this PR.

[gcf-merge-on-green[bot]]

Merge-on-green attempted to merge your PR for 6 hours, but it was not mergeable because either one of your required status checks failed, one of your required reviews was not approved, or there is a do not merge label. Learn more about your required status checks here: https://help.github.com/en/github/administering-a-repository/enabling-required-status-checks. You can remove and reapply the label to re-run the bot.