Add mysql based unit tests

[toshiiw]

• test in the CI environment
• not sure if proper tear down is needed
• maybe add more tests for SQL implemented logic

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This change is 

[k8s-ci-robot]

Hi @toshiiw. Thanks for your PR.

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[YujiOshima]

/ok-to-test

[toshiiw]

seems like I need to tweak workflows.libsonnet to run setup-cluster before unit-test.

[YujiOshima]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: YujiOshima

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[YujiOshima]

/retest

[toshiiw]

/retest