[8.19](backport #48336) terraform: ephemeral tag to help with automated teardown

[mergify]

Proposed commit message

We use cloud-custodian to delete any idling cloud resources used in the CI, for such, we need the ephemeral: true tag.

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• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works. Where relevant, I have used the stresstest.sh script to run them under stress conditions and race detector to verify their stability.
• I have added an entry in ./changelog/fragments using the changelog tool.

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This is an automatic backport of pull request #48336 done by [Mergify](https://mergify.com).

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This pull request has not been merged yet. Could you please review and merge it @v1v? 🙏

[mergify]

This pull request has not been merged yet. Could you please review and merge it @v1v? 🙏