[fix bug] Add preprocess time

[LJH-LBJ]

Description

在metres中添加 preprocess 处理时间
日志输出关键词为Avg preprocess time requests

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring
• Test improvements
• CI/CD improvements

Related Issues

Changes Made

Testing

INFO 12-23 11:27:05 [stats_loggers.py:274] Metrics for ServerType.E_INSTANCE instances:
INFO 12-23 11:27:05 [stats_loggers.py:278] ec_role: E_INSTANCE, addr: ipc:///tmp/encoder_0, Avg e2e time requests: 1229.988 ms, Avg queue time requests: 176.011 ms, Avg prefill time requests: 131.379 ms, Avg preprocess time requests: 922.599 ms, Avg mean time per output token requests: 0.000 ms, Avg time to first token: 0.000 ms, Avg proxy ttft: 0.000 ms, Avg proxy to instance requests time: 46077.688 ms 
INFO 12-23 11:27:05 [stats_loggers.py:274] Metrics for ServerType.PD_INSTANCE instances:
INFO 12-23 11:27:05 [stats_loggers.py:278] ec_role: PD_INSTANCE, addr: ipc:///tmp/prefill_decode_0, Avg e2e time requests: 3668.890 ms, Avg queue time requests: 0.064 ms, Avg prefill time requests: 1130.143 ms, Avg preprocess time requests: 570.354 ms, Avg mean time per output token requests: 65.038 ms, Avg time to first token: 1700.560 ms, Avg proxy ttft: 62300.384 ms, Avg proxy to instance requests time: 13287.602 ms

• Existing tests pass
• New tests added (if applicable)
• Manual testing performed

Test Coverage

Documentation

• Documentation updated (if needed)
• Code comments added/updated
• API documentation updated (if applicable)

Checklist

• I have read the CONTRIBUTING guidelines
• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have signed off my commits (DCO)

Screenshots/Output

Additional Notes

Reviewer Checklist

• Code quality and style
• Test coverage adequate
• Documentation updated
• Performance considerations reviewed
• Security implications considered
• Breaking changes documented