[FIX] find & replace: fix arrow buttons sizing

97b4232 removed the global `box-sizing: content-box;` directive,
but we forgot to add it back to the find & replace buttons.

closes #7317

Task: 5154004
X-original-commit: 0868706
Signed-off-by: Pierre Rousseau (pro) <pro@odoo.com>

Author: hokolomopo

src/components/side_panel/find_and_replace/find_and_replace.ts

@@ -42,6 +42,7 @@ css/* scss */ `
       .o-button {
         height: 19px;
         width: 19px;
+        box-sizing: content-box;
         .o-icon {
           height: 14px;
           width: 14px;