1. In data movement scenario, volumesnapshotcontent by Velero backup will be deleted instead of retained in CSI scenaito, so add
a checkpoint for data movement scenario to verify no volumesnapshotcontent left after Velero backup;
2. Fix global context varaible issue, context varaible is not effective due to it's initialized right after the very beginning of
all tests instead of beginning of each test, so if someone script a new E2E test and did not overwrite it in the test body, then it
will fail the test if it was triggerd one hour later;
3. Due to CSI plugin is deprecated, it breaked down migration tests, because v1.13 still needs to install CSI plugin for the test.
Signed-off-by: danfengl <danfengl@vmware.com>
