UI: remove recently added PIE progress display type

PIE was too similar to RING, as there is no need for two similar display
styles - make only one available.

Removal based on replies to !109882.

source/blender/editors/include/UI_interface.h

@@ -1453,7 +1453,6 @@ enum {
 enum eButProgressType {
   UI_BUT_PROGRESS_TYPE_BAR = 0,
   UI_BUT_PROGRESS_TYPE_RING = 1,
-  UI_BUT_PROGRESS_TYPE_PIE = 2,
 };
 
 /***************************** ID Utilities *******************************/

source/blender/editors/interface/interface_layout.cc

@@ -3510,7 +3510,7 @@ void uiItemProgressIndicator(uiLayout *layout,
                         0,
                         "");
 
-  if (has_text && ELEM(progress_type, UI_BUT_PROGRESS_TYPE_RING, UI_BUT_PROGRESS_TYPE_PIE)) {
+  if (has_text && (progress_type == UI_BUT_PROGRESS_TYPE_RING)) {
     /* For progress bar, centered is okay, left aligned for ring/pie. */
     but->drawflag |= UI_BUT_TEXT_LEFT;
   }

source/blender/editors/interface/interface_widgets.cc

@@ -3640,11 +3640,11 @@ static void widget_progress_type_bar(uiButProgress *but_progress,
 /**
  * Used for both ring & pie types.
  */
-static void widget_progress_type_circle(uiButProgress *but_progress,
-                                        uiWidgetColors *wcol,
-                                        rcti *rect,
-                                        const float ring_width)
+static void widget_progress_type_ring(uiButProgress *but_progress,
+                                      uiWidgetColors *wcol,
+                                      rcti *rect)
 {
+  const float ring_width = 0.6; /* 0.0 would be a pie. */
   const float outer_rad = (rect->ymax - rect->ymin) / 2.0f;
   const float inner_rad = outer_rad * ring_width;
   const float x = rect->xmin + outer_rad;
@@ -3687,12 +3687,8 @@ static void widget_progress_indicator(uiBut *but,
       widget_progress_type_bar(but_progress, wcol, rect, roundboxalign, zoom);
       break;
     }
-    case UI_BUT_PROGRESS_TYPE_PIE: {
-      widget_progress_type_circle(but_progress, wcol, rect, 0.6f);
-      break;
-    }
     case UI_BUT_PROGRESS_TYPE_RING: {
-      widget_progress_type_circle(but_progress, wcol, rect, 0.0f);
+      widget_progress_type_ring(but_progress, wcol, rect);
       break;
     }
   }

source/blender/makesrna/intern/rna_ui_api.cc

@@ -959,7 +959,6 @@ void RNA_api_ui_layout(StructRNA *srna)
   static const EnumPropertyItem progress_type_items[] = {
       {UI_BUT_PROGRESS_TYPE_BAR, "BAR", 0, "Bar", ""},
       {UI_BUT_PROGRESS_TYPE_RING, "RING", 0, "Ring", ""},
-      {UI_BUT_PROGRESS_TYPE_PIE, "PIE", 0, "Pie", ""},
       {0, nullptr, 0, nullptr, nullptr},
   };