Add task to copy CI db in development

What does this MR do and why?

Use a custom rake task in development to copy the CI DB from the main database, if required

This task will be useful on its own for developers to setup a CI DB in their existing installation.

In a follow-up MR, I plan to call this task from GDK's boostrap (see plan: #356349 (comment 884832220))

Related issue: #356349 (closed)

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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