Update to rc21

[manoranjith]

• fix: update docker imgs to rc21
• fix: use bootstrap script in the image

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[manoranjith]

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[cla-bot]

Thank you for your pull request and welcome to our community. We could not parse the GitHub identity of the following contributors: manoranjith.
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