[Chore] Rename SchedulerConfig.chunked_prefill_enabled

[DarkLight1337]

Purpose

SchedulerConfig.chunked_prefill_enabled is redundant with SchedulerConfig.enable_chunked_prefill, so I've renamed all occurrences of the former to the latter. For plugin compatibility, I've deprecated the old property instead of removing it immediately.

Follow-up to #28665 (comment)

Test Plan

Test Result

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[gemini-code-assist]

Code Review

This pull request is a nice cleanup that removes the redundant SchedulerConfig.chunked_prefill_enabled property and replaces all its usages with SchedulerConfig.enable_chunked_prefill. The changes are consistent across the codebase, including configurations, scheduler logic, and tests. The refactoring is well-executed and improves code clarity. I have reviewed all the changes and found no issues. The PR is good to merge.

[njhill]

AFAIK this parameter now only affects the multimodal case when determining max mm items per batch. I wonder whether we should log some warning if it's set to a non-default value since folks might think they can disable prefill chunking when they in fact can't.

But actually is that also what SchedulerConfig.disable_chunked_mm_input does? In which case should we remove chunked_prefill_enabled altogether?

[DarkLight1337]

Hmm, we can control chunked prefill for pooling models though?

[DarkLight1337]

Scheduler code seems to take care of chunked prefill enable/disable, but it's possible that model runner makes some assumptions about that for MM or generative models, not 100% sure about this.

cc @ywang96 @maxdebayser @noooop

[njhill]

Hmm, we can control chunked prefill for pooling models though?

@DarkLight1337 ah sorry yes I missed that. Still I wonder if we should warn in non-pooling case.

[DarkLight1337]

Still I wonder if we should warn in non-pooling case.

In any case let's merge this first. We can update the message in another PR.