Remove `sampler_SkyTexture` and `sampler_MainTex`

ScriptableRenderPipeline/HDRenderPipeline/Lighting/LightLoop/builddispatchindirect.compute

 #include "ShaderLibrary/Common.hlsl"
 #include "LightLoop.cs.hlsl"
 
+#include "../../ShaderVariables.hlsl"
 #define UNITY_MATERIAL_LIT // Need to be define before including Material.hlsl
 #include "../../Material/Material.hlsl" // This includes Material.hlsl
 

ScriptableRenderPipeline/HDRenderPipeline/Lighting/LightLoop/materialflags.compute

 #include "ShaderBase.hlsl"
 #include "LightLoop.cs.hlsl"
 
+#include "../../ShaderVariables.hlsl"
 #define UNITY_MATERIAL_LIT // Need to be define before including Material.hlsl
 #include "../../Material/Material.hlsl" // This includes Material.hlsl
 #include "../../Lighting/LightDefinition.cs.hlsl"

ScriptableRenderPipeline/HDRenderPipeline/Material/GGXConvolution/GGXConvolve.shader

             #include "ShaderLibrary/Common.hlsl"
             #include "ShaderLibrary/ImageBasedLighting.hlsl"
             #include "GGXConvolution.cs.hlsl"
+            #include "../../ShaderVariables.hlsl"
-            SAMPLER(sampler_MainTex);
 
             TEXTURE2D_FLOAT(_GgxIblSamples);
 
                 uint  sampleCount = GetIBLRuntimeFilterSampleCount(_Level);
 
             #ifdef USE_MIS
-                float4 val = IntegrateLD_MIS(TEXTURECUBE_PARAM(_MainTex, sampler_MainTex),
+                float4 val = IntegrateLD_MIS(TEXTURECUBE_PARAM(_MainTex, s_trilinear_clamp_sampler),
                                              _MarginalRowDensities, _ConditionalDensities,
                                              V, N,
                                              roughness,
                                              1024,
                                              false);
             #else
-                float4 val = IntegrateLD(TEXTURECUBE_PARAM(_MainTex, sampler_MainTex),
+                float4 val = IntegrateLD(TEXTURECUBE_PARAM(_MainTex, s_trilinear_clamp_sampler),
                                          _GgxIblSamples,
                                          V, N,
                                          roughness,

ScriptableRenderPipeline/HDRenderPipeline/Sky/SkyVariables.hlsl

 #define UNITY_SKY_VARIABLES_INCLUDED
 
 TEXTURECUBE(_SkyTexture);
-SAMPLER(sampler_SkyTexture); // NOTE: Sampler could be share here with _EnvTextures. Don't know if the shader compiler will complain...
 
 CBUFFER_START(SkyParameters)
 float _SkyTextureMipCount;
 {
-    return SAMPLE_TEXTURECUBE(_SkyTexture, sampler_SkyTexture, texCoord);
+    return SAMPLE_TEXTURECUBE(_SkyTexture, s_trilinear_clamp_sampler, texCoord);
-    return SAMPLE_TEXTURECUBE_LOD(_SkyTexture, sampler_SkyTexture, texCoord, lod);
+    return SAMPLE_TEXTURECUBE_LOD(_SkyTexture, s_trilinear_clamp_sampler, texCoord, lod);
 }
 
 #endif