Some PDF files were not opening in preview because they used a slightly different file type label. This fix ensures those PDFs are recognized correctly, so users can preview them in Documents as expected.

Pdf files marked as mimetype `application/pdf;base64` were not
considered as previewable since the recent refactor to wowl of the
documents views.
This commit fixes it.

The spreadsheet global filter icon now has balanced padding, so it appears properly centered when users hover over it. This improves the visual polish and consistency of the spreadsheet interface.

The padding of the global filter icon wasn't symetric. Because of that,
when hovering the global filter icon it looked like the icon was badly
centered.

Odoo task 2918761

This update corrects a test related to spreadsheet document filters so the automated checks run reliably. It helps maintain quality in the Documents spreadsheet feature without changing how users work with the product.