Replaced the usage of toBeTruthy/toBeFalsy

What does this MR do and why?

Replaced the usage of toBeTruthy/toBeFalsy in spec/frontend/clusters/clusters_bundle_spec.js

Resolves the following issues:

• #369793 (closed)
• #369794 (closed)

Screenshots or screen recordings

How to set up and validate locally

1. Navigate inside gitlab directory
2. Run yarn jest spec/frontend/clusters/clusters_bundle_spec.js
3. Run yarn jest ee/spec/frontend/vue_shared/components/sidebar/epics_select/base_spec.js

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Closes #369793 (closed) Closes #369794 (closed)