[FIX] web_editor: discard background positioning when clicking outside

Since [1] options could still be used while a background positioning
overlay was opened.

After this commit the overlay is deactivated whenever an element outside
of it is clicked - as initially intended.

[1] https://github.com/odoo/odoo/commit/dfd98f49e7f2ab5c94dcae3af2d14750d301fa0a

task-2735690

closes odoo/odoo#82824

X-original-commit: 574ae49acb950d99ef4ab2b0504cfd7f39bca406
Signed-off-by: Romain Derie (rde) <rde@odoo.com>

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

@@ -6773,7 +6773,7 @@ registry.BackgroundPosition = SnippetOptionWidget.extend({
      * @private
      */
     _onDocumentClicked: function (ev) {
-        if (!$(ev.target).closest('.o_we_background_position_overlay')) {
+        if (!$(ev.target).closest('.o_we_background_position_overlay').length) {
             this._toggleBgOverlay(false);
         }
     },