Support gemini-2.5-pro-preview-05-06

[vobolgus]

Summary

Support gemini-2.5-pro-preview-05-06 instead of gemini-2.5-pro-exp-03-25

Description

Please update the currently used Gemini model from gemini-2.5-pro-exp-03-25 to the latest available gemini-2.5-pro-preview-05-06.

Steps to reproduce from a clean Zed install:
1. Set up LLM provider using Gemini
2. Check available models
3. Notice current integration uses the older experimental model gemini-2.5-pro-exp-03-25

Actual Behavior:
Zed defaults to or hardcodes usage of the older experimental model.

Expected Behavior:
Zed should support and default to the newer gemini-2.5-pro-preview-05-06 model for improved performance, up-to-date capabilities, and alignment with the latest Gemini release.

Zed Version and System Specs

Zed: v0.187.0 (Zed Dev d6ab416) (Taylor's Version)
OS: macOS 14.7.5
Memory: 16 GiB
Architecture: aarch64

[asafyish]

#30414
I think it's better to rename to "gemini-2.5-pro-preview" - it seems that when google release new versions they just replace the old one completely.