Blazor Wasm: Virtualize component making 3 initial calls to ItemsProvider instead of 1

When using Virtualize component with ItemsProvider, I have noticed that the ItemsProvider is always called 3 times on the first render. This may be slightly excessive if we are calling an api inside the ItemsProvider.

As an example, I have a collection of 15000 items. On first render, the Virtualize component made 3 calls into the ItemsProvider:
1. Request Count=20, Start Index=0
2. Request Count=21, Start Index=14979 (=15000 - 21)
3. Request Count=21, Start Index=0

I am guessing that the component is doing this for some initial setup calculations of the scroll bar etc...however, the question is whether these 3 calls can be obviated by a single initial call, or is there a way to specify any additional arguments to the component perform its setup without performing 3 calls into ItemsProvider.

Reproduction is here: https://github.com/bancroftway/blazorissuesrepro/tree/dotnet5vscoll

A small video demo is here: https://www.youtube.com/watch?v=5BnRgZTpO0M

Start with the linked dotnet5vscoll reproduction and inspect the Blazor Virtualize component's ItemsProvider calls during first render. Reproduce the three requested ranges, then trace the component's initial measurement and rendering flow. Done means establishing whether the extra calls are expected or changing the behavior with coverage for the reported request sequence.

Written by the indexing model from the issue text.