refactor(gpt-oss): rename eager_attention_forward to eager_attention_forward_with_sink

[casinca]

What does this PR do?

Following: This would resolve #45141

For modularity and also linked to this PR #45144. Potentially re-using mulitple eagers for hybrid models (eg MiMo non-sink/sink eager attn)

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[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: gpt_oss

[Rocketknight1]

Closing this one after comments in #45141!