HDRenderPipeline: Don't add keyword _BLENDMODE_PRESERVE_SPECULAR_LIGHTING if material is not transparent

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Material/Unlit/BaseUnlitUI.cs

             SurfaceType surfaceType = (SurfaceType)material.GetFloat(kSurfaceType);
             CoreUtils.SetKeyword(material, "_SURFACE_TYPE_TRANSPARENT", surfaceType == SurfaceType.Transparent);
 
-            bool enableBlendModePreserveSpecularLighting = material.HasProperty(kEnableBlendModePreserveSpecularLighting) && material.GetFloat(kEnableBlendModePreserveSpecularLighting) > 0.0f;
+            bool enableBlendModePreserveSpecularLighting = (surfaceType == SurfaceType.Transparent) && material.HasProperty(kEnableBlendModePreserveSpecularLighting) && material.GetFloat(kEnableBlendModePreserveSpecularLighting) > 0.0f;
             CoreUtils.SetKeyword(material, "_BLENDMODE_PRESERVE_SPECULAR_LIGHTING", enableBlendModePreserveSpecularLighting);
 
             // These need to always been set either with opaque or transparent! So a users can switch to opaque and remove the keyword correctly