Fix ServiceInstance restore process in migration job

[jasiu001]

This PR is a

• Feature Implementation
• Bug Fix
• Documentation

What this PR does / why we need it:
This short PR fixes the migration process between a version with APIserver and the crds.
During the restore process for ServiceInstance, before creating the resource from the backup data, all information about ClusterServiceClass reference is removed. This information is restored in the update process after creation.
If the creation process fails, then we lose information about ClusterServiceClass reference (before the process the data is overwritten with an empty value). This PR fixes this issue.

Please leave this checklist in the PR comment so that maintainers can ensure a good PR.

Merge Checklist:

• New feature
  • Tests
  • Documentation
• SVCat CLI flag
• Server Flag for config
  • Chart changes
  • removing a flag by marking deprecated and hiding to avoid
    breaking the chart release and existing clients who provide a
    flag that will get an error when they try to update

[k8s-ci-robot]

Hi @jasiu001. Thanks for your PR.

I'm waiting for a kubernetes-sigs or kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[mszostok]

/ok-to-test

[mszostok]

@jasiu001 nice investigation, thanks

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jasiu001, mszostok

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