add klusterlets crd to the cleanup script

[minsikl]

Description of the change: Added klusterlets.operator.open-cluster-management.io to cleanup-managed-cluster.sh to cleanup the crds.

Motivation for the change: It resolves issue #179 . Closes #179

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: minsikl To complete the pull request process, please assign tpouyer after the PR has been reviewed. You can assign the PR to them by writing /assign @tpouyer in a comment when ready.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Kyl-Bempah, minsikl

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• ~~OWNERS~~ [Kyl-Bempah]

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment