Remove feature flag `chat_epic_identifier` and `ai_tool_info`

What does this MR do and why?

Removes the following feature flags:

• chat_epic_identifier #422374 (closed)

• ai_tool_info #422850 (closed)

Both are enabled globally but not enabled by default.

How to set up and validate locally

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #422374 (closed)