There is no step "Select an OS" when creating a .NET 8 (LTS) web app

[v-chenzha]

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OS: Win10 Build Version: 20230910.1 Regression: Not a regression

Repro Steps:

1. F1 -> Azure App Service: Create New Web App... (Advanced) -> Select a subscription -> Enter a name -> Select a resource -> Select ".NET 8 (LTS)" runtime.
2. Check whether the next step is “Select an OS".

Expect: The next step is "Select an OS".

Actual: The next step is "Select a Linux App Service plan".

More Info: This issue doesn't reproduce when creating .NET 6 and .NET 7 web app.