[WebToolsE2E][Green] After installing C# and C# Dev Kit, will encounter warning: "Found markup element with unexpected name 'PageTitle'" in Blazor Web App.

**REGRESSION INFO:** Works well In April release C# DK 3.20.199(C#2.140.9)
**INSTALL STEPS**

OS: Mac x64
Install the SDK 8.0.423
Install VS Code insiders - 1.126.0
Install May prerelease 6 candidate C# devkit 3.21.235(C#2.145.15)

**Platform**

- [x] Windows
- [ ] Linux
- [x] Mac

**REPRO STEPS**

1. Open a normal Terminal Emulator, create Blazor project and open it using VS code insiders
```
md Blazor
cd Blazor
dotnet new blazorserver
code-insiders .
```
2. Open Components/Pages/Home.Razor

**ACTUAL**
Found markup element with unexpected name 'PageTitle'. If this is intended to be a component, add a @using directive for its namespace.

**EXPECTED**
No problems have been detected in the workspace

Reproduce the warning by creating the Blazor project with SDK 8.0.423, opening it in VS Code Insiders, and checking Components/Pages/Home.Razor. Compare the diagnostics with the expected screenshot; done means the PageTitle warning is no longer reported on the supported Windows and Mac setups.

Written by the indexing model from the issue text.