ref(js): Replace substr w/ padStart (#49239)

static/app/components/events/interfaces/frame/frameRegisters/value.tsx

@@ -34,7 +34,7 @@ export function FrameRegisterValue({meta, value}: Props) {
           return `${parsed}`;
         case 0:
         default:
-          return `0x${('0000000000000000' + parsed.toString(16)).substr(-16)}`;
+          return `0x${parsed.toString(16).padStart(16, '0')}`;
       }
     } catch {
       return value;