Add operational readiness template

What does this MR do and why?

Describe in detail what your merge request does and why.

This MR adds a new operational readiness template as a follow-up MR of Introduce next step for AI prototypes to validate operational readiness and fit for purpose

The list was drafted and discussed in https://gitlab.com/gitlab-org/gitlab/-/issues/403859+.

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MR acceptance checklist

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