Support replace_prefix_tokens for verifiers integration

[cmunley1]

Describe the bug

Steps/Code to reproduce bug

Please list minimal steps or code snippet for us to be able to reproduce the bug.

A helpful guide on on how to craft a minimal bug report http://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports.

Expected behavior

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Configs
NeMo Gym (e.g. via ng_dump_config) or RL training framework config files.

Environment details

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• OS version
• Python version
• uv pip list output

Additional context

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