feat(combobox-item): update selection icons (#11726)

**Related Issue:** #10580 

## Summary
Updated selection icons

Author: josercarcamo

packages/calcite-components/src/components/combobox-item/combobox-item.tsx

@@ -279,8 +279,8 @@ export class ComboboxItem extends LitElement implements InteractiveComponent {
       shortHeading,
     } = this;
     const isSingleSelect = isSingleLike(this.selectionMode);
-    const icon = disabled || isSingleSelect ? undefined : "check";
-    const selectionIcon = isSingleSelect ? "bullet-point" : "check";
+    const icon = disabled || isSingleSelect ? undefined : "check-square-f";
+    const selectionIcon = isSingleSelect ? "circle-inset-large" : "check-square-f";
     const headingText = heading || textLabel;
     const itemLabel = label || value;