Remove QPT model ID autofill logic in Agent Registration

[rithin-pullela-aws]

Description

Needs to be merged after #4458

#4458 exposes the agent model ID in params which can be used by tools.

Query Planning Tool has been refactored to use the agent's model ID during agent creation if not explicitly specified during model registration.

Hence the older logic of adding the model ID during QPT registration is not required anymore.

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

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