vllm in-process handles sampling temperature incorrectly

[jlquinn]

Describe the bug

When using decoding method "sample", the temperature is not handled correctly.

1. The default temperature is 0.0, instead of 1.0.
2. If the user sets a temperature, the default of 0.0 will override the user value.

Platform

Please provide details about the environment you are using, including the following:

• Interpreter version: 3.12.7
• Library version: 4151c97

The bug is at vllm_in_proc.py:461