Re-pin vSphere activity date-time guardrail to sortable head

The TrueNAS/vSphere sorting adoption (cf0f027b6) moved the activity
table's When header onto PlatformSortableTableHead, so the guardrail's
literal getPlatformTableHeadClassForKind('numeric-value') pin no longer
matches. The alignment intent survives as the sortable head's
kind="numeric-value" prop; pin that form instead. The metadata-badge
and Button guardrail failures predate the sorting commits and are left
for their owner.

frontend-modern/src/components/shared/SharedPrimitives.guardrails.test.ts

@@ -6015,9 +6015,9 @@ describe('shared primitive guardrails', () => {
       }
     }
 
-    expect(vsphereActivityTableSource).toContain(
-      "getPlatformTableHeadClassForKind('numeric-value')",
-    );
+    // The When header renders through the shared sortable head; the
+    // numeric-value alignment intent now lives on its kind prop.
+    expect(vsphereActivityTableSource).toContain('kind="numeric-value"');
     expect(vsphereActivityTableSource).toContain('minYear={2000}');
   });