Make Claude 3 the default model in Duo

What does this MR do and why?

The Gitlab team is looking to migrate onto these models as part of the 17.0 milestone. The following MR will push in that direction by removing all the code paths related to Claude 1.2.

Remove claude 3 prompt method for chat tools

We are defining all the existing claude 3 prompt tools to default to using Claude 3 by default for the following issues

Changelog: changed EE: true

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Feature	Results
Epic Reader
Issue Reader.
Explain Code
Write Tests
Refactor Code

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