[FIX] web_editor: properly convert background image on retina display

The fix applied by commit [1] for retina displays was not applied in
convert_inline so the bug persisted.

[1]: https://github.com/odoo/odoo/pull/98796/commits/2ea902941221599d4707f5291642b37875bec8c1

opw-3114599

X-original-commit: 1e840ae3619b9d3909e5f8af74b8c48f8d91063c
Part-of: odoo/odoo#111778

addons/web_editor/static/src/js/backend/convert_inline.js

@@ -634,7 +634,7 @@ async function toInline($editable, cssRules, $iframe) {
 async function flattenBackgroundImages(editable) {
     for (const backgroundImage of editable.querySelectorAll('*[style*=background-image]')) {
         if (backgroundImage.parentElement) { // If the image was nested, we removed it already.
-            const canvas = await html2canvas(backgroundImage);
+            const canvas = await html2canvas(backgroundImage, { scale: 1 });
             const image = document.createElement('img');
             image.setAttribute('src', canvas.toDataURL('png'));
             image.setAttribute('width', canvas.getAttribute('width'));