[unity] Removed unnecessary URP shader variants that lead to very high compile time. Closes #1974.

spine-unity/Assets/Spine/Runtime/spine-unity/Shaders/Sprite/SpritesPixelLit.shader

@@ -99,7 +99,6 @@ Shader "Spine/Sprite/Pixel Lit"
 				#pragma fragmentoption ARB_precision_hint_fastest
 				#pragma multi_compile_fog
 				#pragma multi_compile _ PIXELSNAP_ON
-				#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 				#pragma vertex vert
 				#pragma fragment fragBase
@@ -134,7 +133,6 @@ Shader "Spine/Sprite/Pixel Lit"
 				#pragma fragmentoption ARB_precision_hint_fastest
 				#pragma multi_compile_fog
 				#pragma multi_compile _ PIXELSNAP_ON
-				#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 				#pragma vertex vert
 				#pragma fragment fragAdd
@@ -158,7 +156,6 @@ Shader "Spine/Sprite/Pixel Lit"
 				#pragma fragmentoption ARB_precision_hint_fastest
 				#pragma multi_compile_shadowcaster
 				#pragma multi_compile _ PIXELSNAP_ON
-				#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 				#pragma vertex vert
 				#pragma fragment frag

spine-unity/Assets/Spine/Runtime/spine-unity/Shaders/Sprite/SpritesUnlit.shader

@@ -69,7 +69,6 @@ Shader "Spine/Sprite/Unlit"
 				#pragma fragmentoption ARB_precision_hint_fastest
 				#pragma multi_compile_fog
 				#pragma multi_compile _ PIXELSNAP_ON
-				#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 				#pragma vertex vert
 				#pragma fragment frag
@@ -93,7 +92,6 @@ Shader "Spine/Sprite/Unlit"
 				#pragma fragmentoption ARB_precision_hint_fastest
 				#pragma multi_compile_shadowcaster
 				#pragma multi_compile _ PIXELSNAP_ON
-				#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 				#pragma vertex vert
 				#pragma fragment frag

spine-unity/Assets/Spine/Runtime/spine-unity/Shaders/Sprite/SpritesVertexLit.shader

@@ -99,7 +99,6 @@ Shader "Spine/Sprite/Vertex Lit"
 				#pragma fragmentoption ARB_precision_hint_fastest
 				#pragma multi_compile_fog
 				#pragma multi_compile _ PIXELSNAP_ON
-				#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 				#pragma vertex vert
 				#pragma fragment frag
@@ -123,7 +122,6 @@ Shader "Spine/Sprite/Vertex Lit"
 				#pragma fragmentoption ARB_precision_hint_fastest
 				#pragma multi_compile_shadowcaster
 				#pragma multi_compile _ PIXELSNAP_ON
-				#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 				#pragma vertex vert
 				#pragma fragment frag

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/2D/Spine-Sprite-URP-2D.shader

@@ -88,7 +88,6 @@ Shader "Universal Render Pipeline/2D/Spine/Sprite"
 
 			#pragma fragmentoption ARB_precision_hint_fastest
 			#pragma multi_compile _ PIXELSNAP_ON
-			#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 			//--------------------------------------
 			// GPU Instancing
@@ -132,7 +131,6 @@ Shader "Universal Render Pipeline/2D/Spine/Sprite"
 			#pragma shader_feature _ALPHA_CLIP
 
 			#pragma multi_compile _ PIXELSNAP_ON
-			#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 			//--------------------------------------
 			// GPU Instancing

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Spine-Sprite-URP.shader

@@ -99,14 +99,10 @@ Shader "Universal Render Pipeline/Spine/Sprite"
 			#pragma fragmentoption ARB_precision_hint_fastest
 			#pragma multi_compile_fog
 			#pragma multi_compile _ PIXELSNAP_ON
-			#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
 
 			// -------------------------------------
 			// Universal Pipeline keywords
-			#pragma multi_compile _ _MAIN_LIGHT_SHADOWS
-			#pragma multi_compile _ MAIN_LIGHT_CALCULATE_SHADOWS
-			#pragma multi_compile _ REQUIRES_VERTEX_SHADOW_COORD_INTERPOLATOR
-			#pragma multi_compile _ _MAIN_LIGHT_SHADOWS_CASCADE
+			#pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN
 			#pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
 			#pragma multi_compile _ _ADDITIONAL_LIGHT_SHADOWS
 			#pragma multi_compile _ _SHADOWS_SOFT
@@ -116,9 +112,8 @@ Shader "Universal Render Pipeline/Spine/Sprite"
 			// Unity defined keywords
 			#pragma multi_compile _ DIRLIGHTMAP_COMBINED
 			#pragma multi_compile _ LIGHTMAP_ON
-			#pragma multi_compile_fog
 
-			//--------------------------------------
+	//--------------------------------------
 			// GPU Instancing
 			#pragma multi_compile_instancing