[FIX] web_editor: dispose of the tooltip when closing the bg-overlay

Since the migration to Bootstrap 5 (at [1]), the tooltip for the
background position overlay was no longer disposed when toggling the
overlay back on.
This meant that new tooltips kept being added and could lead to a very
confusing user interface.

This was fixed for legacy widgets at [2] but the tooltip for the overlay
is a specific case.

This commit makes disabling the overlay also dispose of the tooltip.

Steps to reproduce:
- Edit a website and drop a cover snippet
- Toggle the background position overlay (by clicking on the target
icon)
- Close the overlay (discard, save or click on the editor)
- Change the Parallax option from fixed to Top to Bottom (this is just
so that the previous tooltip is clearly visible after the next step)
- Toggle the background overlay again
=> The old tooltip is still present and a new one is visible

[1]: https://github.com/odoo/odoo/commit/1fcd098af5fa18e848c66bb83bdceb6ba0308512
[2]: https://github.com/odoo/odoo/commit/3c01b1cd77adec146b1a90f96bb1223a2108678b

task-3119958

closes odoo/odoo#110170

X-original-commit: 2ddffeef579baf47ff117b133a9d4fbf12108a2c
Signed-off-by: Bojabza Soukéina (sobo) <sobo@odoo.com>

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

@@ -7222,6 +7222,9 @@ registry.BackgroundPosition = SnippetOptionWidget.extend({
             this.trigger_up('activate_snippet', {$snippet: this.$target});
 
             $(document).off('click.bgposition');
+            if (this.$bgDragger) {
+                this.$bgDragger.tooltip('dispose');
+            }
             return;
         }