[Blazor] Investigate adjusting the default buffer size for component RenderTrees

From the profile about 2% of the time is spent on GrowBuffer.

Every time we do so it means that we rent a new array, we copy the elements and we return the existing one. Adjusting the default size should allow us to reduce the times we need to do this.

Start by locating GrowBuffer and the default buffer size used for component RenderTrees. Profile or benchmark representative rendering workloads before and after the adjustment, and verify that fewer buffer growth operations occur without introducing regressions or excessive memory use.

Written by the indexing model from the issue text.