Some comments removed during MCP migration

Testing #335626

Write the following to `.vscode/mcp.json`:
```jsonc
{
"servers": {

// This is the migrate-me server
"migrate-me": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@modelcontextprotocol/server-everything"
]
},

// This is the leave-me server
"leave-me": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@modelcontextprotocol/server-everything"
]
},
}
}
```

Then migrate the `migrate-me` server. Afterwards `.vscode/mcp.json` becomes:
```jsonc
{
"servers": {
"leave-me": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@modelcontextprotocol/server-everything"
]
},
}
}
```

Notice that the comment on `leave-me` is lost.