Updated location of istioctl. (#633)
Updated location of istioctl. (#633)

Automatic merge from submit-queue.

Updated location of istioctl.

Updated the file path for ISTIOCTL_URL so it points to the new location.

```release-note
Updated the file path for that ISTIOCTL_URL uses in the githubctl tool to reflect the new file path
```
istio/test-infra,istio/test-infra,istio/test-infra,istio/test-infra