fake-client in UTs

[Garvit-77]

What this PR does / why we need it:
This PR implements Changes of UTs with fake client instead of gomock
Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #2408

Checklist:

• [Y] Docs included if any changes are user facing

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign gaocegege for approval. For more information see the Kubernetes Code Review Process.

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

[Garvit-77]

Hey @tenzen-y
Please let me know any changes and
I think KatibClientMock does have the function for handling fake client should i create that with this pr ?

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[github-actions]

This pull request has been automatically closed because it has not had recent activity. Please comment "/reopen" to reopen it.