Revert "Use LazyValue for routed_experts_weights_of_layer initialization"

[longxin9715]

PR Title

Revert "Use LazyValue for routed_experts_weights_of_layer initialization"

Motivation

Original PR ：sgl-project#15904
Revert the modification of wrapping routed_experts_weights_of_layer with LazyValue.
After using LazyValue, the expert load balancing logic fails to execute correctly, causing runtime errors in MoE expert scheduling and load balancing.
Restore the original direct initialization to ensure normal operation of expert load balancing.

Modifications

1. Revert code block of routed_experts_weights_of_layer assignment logic
2. Remove LazyValue wrapper and lambda expression
3. Restore original direct dict eager initialization implementation

Accuracy Tests

N/A
Pure logic revert, no impact on model accuracy and output results.

Benchmarking and Profiling

N/A
No inference performance changes introduced.

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests.
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.
• Follow the SGLang code style guidance.

Review Process

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2. Get approvals from CODEOWNERS and other reviewers.
3. Trigger CI tests with comments or contact authorized users to do so.
   • /tag-run-ci-label, /rerun-failed-ci, /tag-and-rerun-ci
4. After green CI and required approvals, ask Merge Oncalls to merge.

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