Make isReadinessApplicable static

[LarsSven]

Description

Recently, a change was made to make isReadinessApplicable public such that it can be used within Quarkus rather than needing to duplicate the method (134808e). However, it is a non-static method, so you have to create a Readiness instance before you can use it, which is unnecessary.

This Makes it static so that this method can be used without needing to instantiate an instance of Readiness.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change
• Chore (non-breaking change which doesn't affect codebase;
  test, version modification, documentation, etc.)

Checklist

• Code contributed by me aligns with current project license: Apache 2.0
• I Added CHANGELOG entry regarding this change
• I have implemented unit tests to cover my changes
• I have added/updated the javadocs and other documentation accordingly
• No new bugs, code smells, etc. in SonarCloud report
• I tested my code in Kubernetes
• I tested my code in OpenShift