Sync eng/common directory with azure-sdk-tools for PR 14709

[azure-sdk]

Sync eng/common directory with azure-sdk-tools for PR Azure/azure-sdk-tools#14709 See eng/common workflow

[Copilot]

Pull request overview

This PR syncs the eng/common MCP installer script with the corresponding changes from azure-sdk-tools PR 14709, updating how the azsdk CLI/MCP server is installed and invoked.

Changes:

• Removes configurable FileName/Package parameters and hardcodes azsdk / Azure.Sdk.Tools.Cli values.
• Adds a fast-path to detect an existing azsdk install and skip reinstall if the requested/latest version is already present.
• Adjusts process invocation to run the azsdk mcp command and propagates the child process exit code.

Comments suppressed due to low confidence (1)

eng/common/mcp/azure-sdk-mcp.ps1:156

• In the non-MCP branch, the final line of the Install-Standalone-Tool invocation ends with a backtick line-continuation (after -Repository $Repository). That makes the command continue onto the next line (}), which will cause a parse/syntax error when running the script. Remove the trailing backtick (or add the intended continuation) so the call terminates correctly.

    $tempExe = Install-Standalone-Tool `
        -Version $Version `
        -FileName $packageFileName `
        -Package $packageName `
        -Directory $tempInstallDirectory `
        -Repository $Repository `

}