Automatic merge from submit-queue (batch tested with PRs 44591, 44549)
[Federation][e2e] Fix a failing federation e2e testcase in gce-serial
This is to fix the failing test case in federation [gce-serial](https://k8s-testgrid.appspot.com/cluster-federation#gce-serial) tests. The test case has been failing consistently since we registered the clusters in suite-init instead of doing it in every test case.
Instead of registering and then unregistering, we will be now unregistering and then registering the cluster to federation. this test will be run in serial and will not affect other test cases too.
**Release note**:
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