Remove InsertBeamSearchOp pass

[devang-ml]

Describe your changes

BeamSearchOp is deprecated and not actively supported. The plan is to use generative APIs to do beam search op.

Remove examples and pass that uses this Op.

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• Lint and apply fixes to your code by running lintrunner -a
• Is this a user-facing change? If yes, give a description of this change to be included in the release notes.
• Is this PR including examples changes? If yes, please remember to update example documentation in a follow-up PR.

(Optional) Issue link