operator/pkg: mitigate null pointer dereference in `Validate()` and `newRunData()` functions

[mohamedawnallah]

Description

In this commit, we mitigate the null pointer dereference issue in the deinit operator pkg by adding defensive checks on opt.Karmada.Spec.HostCluster in newRunData func and on opt.Karmada.Spec.Components in Validate in init.go.

Motivation and Context

While unit testing the Karmada Init and DeInit in the operator package (#5613), deliberately passing empty components on those fields triggers a null pointer exception error. This PR resolves this issue by adding defensive checks.

While testing

What type of PR is this?

/kind cleanup

Does this PR introduce a user-facing change?:

NONE