fix(): New UTs for SliceValidationWebhook

[priyank-upadhyay]

Description

Unit tests for NoNetwork scenarios

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Checklist:

• The title of the PR states what changed and the related issues number (used for the release note).
• Does this PR requires documentation updates?
• I've updated documentation as required by this PR.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have tested it for all user roles.
• I have added all the required unit test cases.

Does this PR introduce a breaking change for other components like worker-operator?

[priyank-upadhyay]

❯ make unit-test
go test -gcflags=-l ./service --coverprofile=coverage.out
ok      github.com/kubeslice/kubeslice-controller/service       1.649s  coverage: 80.2% of statements