This should avoids the size regression on WebAssembly and possibly other
platforms without Sse2.

The regression is side effect of dotnet#78861
which uses `PackedSpanHelpers.CanUsePackedIndexOf (!!T)` and TShouldUsePacked.Value
to guard the usage of PackedSpanHelpers.

Because these involve generics, illinker is unable to link
the PackedSpanHelpers type away and that pulls other parts in, like
System.Runtime.Intrinsics.X86.* types. See https://gist.github.com/radekdoulik/c0b52247d472f69bcf983ade78a924ea
for more complete list.

This change gets us back 9,216 bytes in the case of app used to repro
the regression.

    ...
      -             Type System.PackedSpanHelpers
      -             Type System.Runtime.Intrinsics.X86.X86Base
      -             Type System.Runtime.Intrinsics.X86.Sse
      -             Type System.Runtime.Intrinsics.X86.Sse2
    Summary:
      -       9,216 File size -0.76% (of 1,215,488)
      -       2,744 Metadata size -0.43% (of 636,264)
      -           4 Types count

…es/IndexOfAnyValues.cs

Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>

…es/IndexOfAnyValues.cs

Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>