fix(stepper-item): remove delay in highlighting item (#8996)

**Related Issue:** #6482

## Summary
Removed delay in highlighting a stepper item.

packages/calcite-components/src/components/stepper-item/stepper-item.scss

@@ -264,7 +264,7 @@
     grid-row: items;
 
     &:focus {
-      @apply focus-outset;
+      @apply focus-outset duration-0;
     }
   }
 
@@ -276,6 +276,12 @@
   }
 }
 
+:host([layout="vertical"]) {
+  .stepper-item-header:focus {
+    @apply duration-0;
+  }
+}
+
 :host([layout="horizontal"][disabled]),
 :host([layout="horizontal-single"][disabled]) {
   .stepper-item-header {