fix: mcp-bridge flaky test

[nic-6443]

Background

In previous tests, the MCP Server was started using the following command:

pnpm dlx @modelcontextprotocol/[email protected]

However, during repeated test runs, this approach was found to cause unstable sub-dependency resolution. Different runs could resolve different versions of transitive dependencies, leading to MCP Server startup failures or inconsistent behavior, which negatively impacted test reliability.

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Changes

To ensure stability and reproducibility of the test environment, this PR updates the build process for [email protected] as follows:

1. Stop using pnpm dlx to dynamically fetch and execute the package
2. Download the corresponding versioned source archive from the official repository:
   https://github.com/modelcontextprotocol/servers/archive/refs/tags/2025.7.1.tar.gz
3. Manually build the [email protected] MCP Server using the included package-lock.json
4. Lock the entire dependency tree to ensure consistent dependency versions across all test runs

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Scope of Impact

• Only affects the build and startup process of the MCP Server ([email protected])
• No functional or behavioral changes to the server itself

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[membphis]

@LiteSun still one test case failed, pls fix it