Do a pass through docs to ensure that IsAspireHost is not part of an AppHost project

[joperezr]

With PR dotnet/aspire#8144, newer AppHost projects will no longer have the property IsAspireHost set in them, as this will now flow from the SDK. This issue is to track the work of doing a pass through all of our docs that may have a mention of this property, or alternatively snippets that may have it, and making sure that it is updated.

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Associated WorkItem - 408619