test(module): add test for discovery nodes hook

[fl64]

Description

add test for discovery nodes hook

Why do we need it, and what problem does it solve?

What is the expected result?

Checklist

• [ ] The code is covered by unit tests.
• [ ] e2e tests passed.
• [ ] Documentation updated according to the changes.
• [ ] Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: module
type: chore
summary: add test for discovery nodes hook
impact_level: low