[BUG][The start.sh script uses same Downstream Builds SNAPSHOTS version for multiclusterengine operator]

[Prashant Dhamdhere]

Describe the bug
The start.sh script uses same Downstream Builds SNAPSHOTS version while installing multiclusterengine operator.
The catlogsource of multiclusterengine uses following image instead of latest tag from https://quay.io/repository/acm-d/mce-custom-registry?tab=tags after execute start.sh script.

Example:

$ cat catalogsources/multicluster-engine.yaml |grep image
  image: "quay.io:443/acm-d/mce-custom-registry:2.5.0-DOWNSTREAM-2022-01-24-16-34-41"

The below events reported by catlogsource pod of multiclusterengine

Events:
  Type     Reason          Age                  From               Message
  ----     ------          ----                 ----               -------
  Normal   Scheduled       2m22s                default-scheduler  Successfully assigned openshift-marketplace/multiclusterengine-catalog-f6bbc to pdhamdhe25acm-m6n5l-worker-centralus3-k9zcs
  Normal   AddedInterface  2m20s                multus             Add eth0 [10.128.2.73/23] from openshift-sdn
  Warning  Failed          56s (x6 over 2m19s)  kubelet            Error: ImagePullBackOff
  Normal   Pulling         45s (x4 over 2m20s)  kubelet            Pulling image "quay.io:443/acm-d/mce-custom-registry:2.5.0-DOWNSTREAM-2022-01-24-16-34-41"
  Warning  Failed          44s (x4 over 2m19s)  kubelet            Failed to pull image "quay.io:443/acm-d/mce-custom-registry:2.5.0-DOWNSTREAM-2022-01-24-16-34-41": rpc error: code = Unknown desc = reading manifest 2.5.0-DOWNSTREAM-2022-01-24-16-34-41 in quay.io:443/acm-d/mce-custom-registry: manifest unknown: manifest unknown
  Warning  Failed          44s (x4 over 2m19s)  kubelet            Error: ErrImagePull
  Normal   BackOff         30s (x7 over 2m19s)  kubelet            Back-off pulling image "quay.io:443/acm-d/mce-custom-registry:2.5.0-DOWNSTREAM-2022-01-24-16-34-41"

To Reproduce
Steps to reproduce the behavior:

1. Deploy ACM as per https://github.com/stolostron/deploy#deploy-using-the-startsh-script-the-easy-way
2. After execute start.sh script the catlogsource pod of multiclusterengine goes in Error: ImagePullBackOff
3. Check the logs of multiclusterengine catlogsource pod which show SNAPSHOTS tag is getting used in image

Expected behavior
The start.sh script should use multiclusterengine tag from https://quay.io/repository/acm-d/mce-custom-registry?tab=tags
Need to update the start.sh script to use correct multiclusterengine tag