[FIX] web_editor: restore transitions when finding a gradient background

Since [1] the class `o_we_force_no_transition` was not removed when
selecting a snippet when the background color was a gradient. (It was
however removed when selecting a background color.)

After this commit the class is removed in that situation just like for
any other `data-select-style` attribute.

[1]: https://github.com/odoo/odoo/commit/a48a30f954afcb6ff3a59c4f32b05fd0c2cfcd2b

task-2633169

closes odoo/odoo#86126

X-original-commit: ed530aef3c6d99712db055099b5f06a31e91d9cf
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>
Signed-off-by: Benoit Socias (bso) <bso@odoo.com>

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

@@ -3607,6 +3607,7 @@ const SnippetOptionWidget = Widget.extend({
                     // if editing the other).
                     const parts = backgroundImageCssToParts(styles['background-image']);
                     if (parts.gradient) {
+                        _restoreTransitions();
                         return parts.gradient;
                     }
                 }