MC-18709: [WYSIWYG]Spinner is Always Displayed on Media Gallery popup

Author: vitalysery

lib/web/mage/loader.js

@@ -69,7 +69,10 @@ define([
         show: function (e, ctx) {
             this._render();
             this.loaderStarted++;
-            this.spinner.show();
+
+            if (this.loaderStarted === 1) {
+                this.spinner.show();
+            }
 
             if (ctx) {
                 this.spinner

lib/web/mage/loader_old.js

@@ -81,7 +81,10 @@
         show: function (e, ctx) {
             this._render();
             this.loaderStarted++;
-            this.spinner.show();
+
+            if (this.loaderStarted === 1) {
+                this.spinner.show();
+            }
 
             if (ctx) {
                 this.spinner