Keywords for Evaluate SH and SoftShadows are incorrectly set up in ShaderGraph.

Instead of being:
{code:java}
#pragma multi_compile_fragment _ _SHADOWS_SOFT _SHADOWS_SOFT_LOW _SHADOWS_SOFT_MEDIUM _SHADOWS_SOFT_HIGH
#pragma multi_compile _ EVALUATE_SH_MIXED EVALUATE_SH_VERTEX
{code}

They are:
{code:java}
#pragma multi_compile_fragment _ _SHADOWS_SOFT
#pragma multi_compile_fragment _ _SHADOWS_SOFT_LOW
#pragma multi_compile_fragment _ _SHADOWS_SOFT_MEDIUM
#pragma multi_compile_fragment _ _SHADOWS_SOFT_HIGH
#pragma multi_compile _ EVALUATE_SH_MIXED
#pragma multi_compile _ EVALUATE_SH_VERTEX
{code}

This adds more variants than needed and breaks functionality with those features.

The regressions came from these PRs
* [SH Regression|https://github.cds.internal.unity3d.com/unity/unity/pull/39802]
* [SoftShadow Regression|https://github.cds.internal.unity3d.com/unity/unity/pull/31962]