Completion builder prefers regular completions over built ones and activates them in lambda parameters

VS 17.11.0 P2.1

Completion session controller should select the built completion when naming variables (in this case lambda expression parameter name), instead of matching the existing symbols or regular completions provided.

This makes writing lambda expressions quite frustrating, because every time it completes the name I try to assign to a completion from the list.

https://github.com/dotnet/roslyn/assets/9047283/4ccebacf-33a8-46c9-ad28-bba30c7d5208

```razor
@code {
protected override void OnInitialized()
{
int[] numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
var even = numbers.Where(n$$);
base.OnInitialized();
}
}
```