Fix stderr output

[aheizi]

Fix stderr output, stderr outputs only the error log. Other logs are output to stdout.

Motivation and Context

Now the stderr contains both error logs and info logs. When the business outputs to stderr, it mistakenly outputs the info logs to the user as well.

For example, previously dependent parties might have needed to filter out info logs themselves

• fix mcp stderr log RooVetGit/Roo-Code#1830
• Hide INFO level MCP Server stderr log messages cline/cline#2468

How Has This Been Tested?

use roo-code tested

Breaking Changes

Types of changes

• 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 change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context