"getWslProfiles" blocks main thread via synchronous "CreateProcessW"

Does this issue occur when all extensions are disabled?: Yes

- VS Code Version: 1.107.1
- OS Version: Windows 10/11 (x64) with WSL installed

## Bug Description

`getWslProfiles()` in `src/vs/platform/terminal/node/terminalProfiles.ts` calls `cp.exec("wsl.exe -l -q")` synchronously on the main thread (CrBrowserMain / Node.js event loop). On Windows, `uv_spawn` → `CreateProcessW` → `NtCreateUserProcess` is a **blocking kernel call** that can stall the main thread for **100ms to 6+ seconds**, causing full UI freeze.

## Root Cause

The `cp.exec("wsl.exe -l -q")` call in `getWslProfiles` (terminalProfiles.ts:347-358) executes on the main thread. On Windows, libuv's `uv_spawn` invokes `CreateProcessW` which is a synchronous kernel call — the `timeout: 1000` option only limits stdout wait time, **not** the process creation itself.

`wsl.exe` is particularly slow to spawn because:
1. WSL subsystem cold-start may require launching a lightweight VM / Hyper-V instance
2. Antivirus software (Windows Defender, etc.) hooks and scans `CreateProcess`
3. Kernel resource contention under high system load

## Call Stack (native + JS, sourcemap-resolved)
- native call stack
[crash_stack (1).txt](https://github.com/user-attachments/files/30196545/crash_stack.1.txt)
- node js call stack
```
at getWslProfiles (lib/vscode/src/vs/platform/terminal/node/terminalProfiles.ts:151:24)
const result = await getWslProfiles(`${system32Path}\\wsl.exe`, defaultProfileName);
at ube (lib/vscode/src/vs/platform/terminal/node/terminalProfiles.ts:349:28)
const distroOutput = await new Promise((resolve, reject) =>
at new Promise ()
at r (lib/vscode/src/vs/platform/terminal/node/terminalProfiles.ts:352:5)
cp.exec('wsl.exe -l -q', { encoding: 'utf16le', env: { ...process.env, WSL_UTF8: '0' }, timeout: 1000 }, (err, stdout) =>
at Module.exec (node:child_process:236:25)
at t. [as execFile] (node:electron/js2c/node_init:2:3013)
at Object.execFile (node:child_process:349:17)
at spawn (node:child_process:801:9)
at ChildProcess.spawn (node:internal/child_process:422:13)
at process.nextTick (node:electron/js2c/browser_init:2:149394)
```

## Steps to Reproduce

1. Use VS Code on Windows with WSL installed (especially with multiple distros).
2. Open VS Code — terminal profile detection runs automatically on startup.
3. Open the terminal dropdown or create a new terminal instance.
4. Observe UI freeze/jank for 100ms~seconds while `wsl.exe -l -q` spawns.
5. Reproduction is more reliable when: WSL has not been used recently (cold start), antivirus is active, or system is under load.

## Expected Behavior

Terminal profile detection should not block the main thread. The UI should remain responsive during WSL profile enumeration.