[FIX] website: restore carousel item behavior

The animation that made all the carousel items have the same height
automatically was broken. This commit fixes it and improves its behavior
during edition.

closes odoo/odoo#27801

addons/website/static/src/js/content/snippets.animation.js

@@ -426,27 +426,16 @@ var registry = {};
 
 registry.slider = Animation.extend({
     selector: '.carousel',
+    edit_events: {
+        'slid.bs.carousel': '_onEditionSlide',
+    },
 
     /**
      * @override
      */
     start: function () {
         if (!this.editableMode) {
-            var maxHeight = 0;
-            var $items = this.$('.item');
-            _.each($items, function (el) {
-                var $item = $(el);
-                var isActive =  $item.hasClass('active');
-                $item.addClass('active');
-                var height = $item.outerHeight();
-                if (height > maxHeight) {
-                    maxHeight = height;
-                }
-                $item.toggleClass('active', isActive);
-            });
-            _.each($items, function (el) {
-                $(el).css('min-height', maxHeight);
-            });
+            this._computeHeights();
         }
         this.$target.carousel();
         return this._super.apply(this, arguments);
@@ -458,10 +447,46 @@ registry.slider = Animation.extend({
         this._super.apply(this, arguments);
         this.$target.carousel('pause');
         this.$target.removeData('bs.carousel');
-        _.each(this.$('.item'), function (el) {
+        _.each(this.$('.carousel-item'), function (el) {
             $(el).css('min-height', '');
         });
     },
+
+    //--------------------------------------------------------------------------
+    // Private
+    //--------------------------------------------------------------------------
+
+    /**
+     * @private
+     */
+    _computeHeights: function () {
+        var maxHeight = 0;
+        var $items = this.$('.carousel-item');
+        _.each($items, function (el) {
+            var $item = $(el);
+            var isActive = $item.hasClass('active');
+            $item.addClass('active');
+            var height = $item.outerHeight();
+            if (height > maxHeight) {
+                maxHeight = height;
+            }
+            $item.toggleClass('active', isActive);
+        });
+        _.each($items, function (el) {
+            $(el).css('min-height', maxHeight);
+        });
+    },
+
+    //--------------------------------------------------------------------------
+    // Handlers
+    //--------------------------------------------------------------------------
+
+    /**
+     * @private
+     */
+    _onEditionSlide: function () {
+        this._computeHeights();
+    },
 });
 
 registry.parallax = Animation.extend({

addons/website/static/src/js/editor/snippets.options.js

@@ -247,6 +247,10 @@ options.registry.carousel = options.Class.extend({
                 }
             });
             _.defer(function () {
+                self.trigger_up('animation_start_demand', {
+                    editableMode: true,
+                    $target: self.$target,
+                });
                 self.$target.carousel(index > 0 ? --index : cycle);
             });
         }