fix: do not apply the color domain order for the unstacked ungrouped chart (#9687)

As titled;

The existing logic applied the order by domain for
non-stacked/non-grouped chart (such as color line without stack) so it
breaks the order of the path.

This PR fixes it. (see the example commit by commit)

---------

Co-authored-by: GitHub Actions Bot <vega-actions-bot@users.noreply.github.com>

Author: yhoonkim

examples/compiled/bar_diverging_stack_transform.svg

@@ -282,11 +282,6 @@
         },
         {"type": "formula", "expr": "datum.v1 - datum.offset", "as": "nx"},
         {"type": "formula", "expr": "datum.v2 - datum.offset", "as": "nx2"},
-        {
-          "type": "formula",
-          "expr": "indexof([\"Strongly disagree\",\"Disagree\",\"Neither agree nor disagree\",\"Agree\",\"Strongly agree\"], datum['type'])",
-          "as": "_type_sort_index"
-        },
         {
           "type": "filter",
           "expr": "isValid(datum[\"nx\"]) && isFinite(+datum[\"nx\"])"
@@ -306,10 +301,6 @@
       "name": "marks",
       "type": "rect",
       "style": ["bar"],
-      "sort": {
-        "field": ["datum[\"_type_sort_index\"]"],
-        "order": ["ascending"]
-      },
       "from": {"data": "data_0"},
       "encode": {
         "update": {

examples/compiled/bar_diverging_stack_transform.vg.json

@@ -12,6 +12,11 @@
       "url": "data/londonBoroughs.json",
       "format": {"type": "topojson", "feature": "boroughs"}
     },
+    {
+      "name": "source_2",
+      "url": "data/londonTubeLines.json",
+      "format": {"type": "topojson", "feature": "line"}
+    },
     {
       "name": "source_1",
       "url": "data/londonCentroids.json",
@@ -34,18 +39,6 @@
           "as": ["layer_1_x", "layer_1_y"]
         }
       ]
-    },
-    {
-      "name": "source_2",
-      "url": "data/londonTubeLines.json",
-      "format": {"type": "topojson", "feature": "line"},
-      "transform": [
-        {
-          "type": "formula",
-          "expr": "indexof([\"Bakerloo\",\"Central\",\"Circle\",\"District\",\"DLR\",\"Hammersmith & City\",\"Jubilee\",\"Metropolitan\",\"Northern\",\"Piccadilly\",\"Victoria\",\"Waterloo & City\"], datum['id'])",
-          "as": "_id_sort_index"
-        }
-      ]
     }
   ],
   "projections": [
@@ -100,7 +93,6 @@
       "name": "layer_2_marks",
       "type": "shape",
       "style": ["geoshape"],
-      "sort": {"field": ["datum[\"_id_sort_index\"]"], "order": ["descending"]},
       "from": {"data": "source_2"},
       "encode": {
         "update": {

examples/compiled/geo_layer_line_london.png

@@ -45,20 +45,9 @@
         {"country": "United States", "animal": "sheep", "col": 1}
       ]
     },
-    {
-      "name": "data_0",
-      "source": "source_0",
-      "transform": [
-        {
-          "type": "formula",
-          "expr": "indexof([\"person\",\"cattle\",\"pigs\",\"sheep\"], datum['animal'])",
-          "as": "_animal_sort_index"
-        }
-      ]
-    },
     {
       "name": "row_domain",
-      "source": "data_0",
+      "source": "source_0",
       "transform": [{"type": "aggregate", "groupby": ["country"]}]
     }
   ],
@@ -90,7 +79,7 @@
       "type": "group",
       "style": "cell",
       "from": {
-        "facet": {"name": "facet", "data": "data_0", "groupby": ["country"]}
+        "facet": {"name": "facet", "data": "source_0", "groupby": ["country"]}
       },
       "sort": {"field": ["datum[\"country\"]"], "order": ["ascending"]},
       "encode": {
@@ -104,10 +93,6 @@
           "name": "child_marks",
           "type": "symbol",
           "style": ["point"],
-          "sort": {
-            "field": ["datum[\"_animal_sort_index\"]"],
-            "order": ["descending"]
-          },
           "from": {"data": "facet"},
           "encode": {
             "update": {
@@ -131,14 +116,14 @@
     {
       "name": "x",
       "type": "point",
-      "domain": {"data": "data_0", "field": "col", "sort": true},
+      "domain": {"data": "source_0", "field": "col", "sort": true},
       "range": [0, {"signal": "child_width"}],
       "padding": 0.5
     },
     {
       "name": "y",
       "type": "point",
-      "domain": {"data": "data_0", "field": "animal", "sort": true},
+      "domain": {"data": "source_0", "field": "animal", "sort": true},
       "range": [0, {"signal": "child_height"}],
       "padding": 0.5
     },

examples/compiled/geo_layer_line_london.svg

@@ -38,17 +38,6 @@
           "expr": "isValid(datum[\"num_cars\"]) && isFinite(+datum[\"num_cars\"])"
         }
       ]
-    },
-    {
-      "name": "data_1",
-      "source": "source_0",
-      "transform": [
-        {
-          "type": "formula",
-          "expr": "indexof([false,true], datum['more_than_half'])",
-          "as": "_more_than_half_sort_index"
-        }
-      ]
     }
   ],
   "signals": [
@@ -80,11 +69,7 @@
       "name": "layer_1_marks",
       "type": "text",
       "style": ["text"],
-      "sort": {
-        "field": ["datum[\"_more_than_half_sort_index\"]"],
-        "order": ["descending"]
-      },
-      "from": {"data": "data_1"},
+      "from": {"data": "source_0"},
       "encode": {
         "update": {
           "fill": {"scale": "layer_1_color", "field": "more_than_half"},
@@ -107,7 +92,7 @@
       "domain": {
         "fields": [
           {"data": "data_0", "field": "Cylinders"},
-          {"data": "data_1", "field": "Cylinders"}
+          {"data": "source_0", "field": "Cylinders"}
         ],
         "sort": true
       },
@@ -121,7 +106,7 @@
       "domain": {
         "fields": [
           {"data": "data_0", "field": "Origin"},
-          {"data": "data_1", "field": "Origin"}
+          {"data": "source_0", "field": "Origin"}
         ],
         "sort": true
       },