feat: hide ci editor tool behind feature flag

What does this merge request do and why?

CiEditor tool doesn't bring a lot of value and we're going to remove it. Chat is capable of answering those questions without the tool so this change will improve (a bit) performance for users as it skips one request to LLM as well as removes burden of maintaining the tool.

With this change nothing really changes as the feature flag isn't implemented in Rails yet.

How to set up and validate locally

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

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.