First navigation to external source always fails

**Version Used**:
Latest VS 2026 [11201.2]

**Steps to Reproduce**:
1. Go to `C:\Users\\AppData\Local\Temp\SymbolCache\System.Private.CoreLib.pdb`
2. Delete all folders there
3. In VS open file containing:
```cs
int a;
```
4. Go to definition on `int`

**Expected Behavior**:
There is a short delay due to symbols being downloaded, then I am navigated to source of `Int32`

**Actual Behavior**:
There is a short delay, but them I am navigated to _metadata_ representation of `Int32`, not source. The `Navigate to External Sources` log channel is the following:
```
Navigating to symbol 'int' from 'System.Runtime'.
Symbol found in assembly path 'C:\Program Files\dotnet\packs\Microsoft.NETCore.App.Ref\8.0.21\ref\net8.0\System.Runtime.dll'
Symbol found in assembly path 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\8.0.21\System.Runtime.dll'
Symbol found in assembly path 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\8.0.21\System.Private.CoreLib.dll'
Timed out trying to download PDB from symbol server. Subsequent requests may succeed.
```
See the last line where it says about timeout. But in reality this is not true. If you now look into the folder with symbol cache, it now contains a subfolder with perfectly fine pdb inside, so dowbload did complete successfully. Moreover, subsequent attempts to go to definition of `int` will succeed almost immideatelly, so downloaded pdb isn't corrupted or something. It is just that the first time after downloading pdb VS doesn't process things correctly and fails with "timeout" instead of using that pdb