[IMP] website_slides: remove unique slide name constraint within channel

Having a unique constraint for a slide name in a channel look strange.
It force an RPC call to check this when uploading a slide, making the
process a little bit slow.
Morevover, name is a translatable field on slide.slide model, so the
constraint can not be fully respected.

To simplify the model, we decided to remove this.

Task-1938643

addons/website_slides/models/slide_slide.py

@@ -101,10 +101,6 @@ class Slide(models.Model):
         'channel_id', 'description', 'tag_ids', 'write_date', 'create_date',
         'website_published', 'website_url', 'website_meta_title', 'website_meta_description', 'website_meta_keywords', 'website_meta_og_img']
 
-    _sql_constraints = [
-        ('name_uniq', 'UNIQUE(channel_id, name)', 'The slide name must be unique within a channel')
-    ]
-
     # description
     name = fields.Char('Title', required=True, translate=True)
     active = fields.Boolean(default=True)

addons/website_slides/static/src/js/slides_upload.js

@@ -51,17 +51,6 @@ var SlideDialog = Widget.extend({
     // Private
     //--------------------------------------------------------------------------
 
-    /**
-     * @private
-     * @param {string} file_name
-     */
-    _checkUniqueSlide: function (fileName) {
-        return this._rpc({
-            model: 'slide.slide',
-            method: 'search_count',
-            args: [[['channel_id', '=', self.channelId], ['name', '=', fileName]]],
-        });
-    },
     /**
      * @private
      */
@@ -405,13 +394,7 @@ var SlideDialog = Widget.extend({
 
         var input = file.name;
         var inputVal = input.substr(0, input.lastIndexOf('.')) || input;
-        this._checkUniqueSlide(inputVal).then(function (exist) {
-            if (exist) {
-                var message = _t("Channel contains the given title, please change before Save or Publish.");
-                self._displayAlert(message);
-            }
-            self.$('#name').val(inputVal);
-        });
+        this.$('#name').val(inputVal);
     },
     /**
      * @private