Cleanup dead code related to disabled Akeyless secrets integration feature

Why this MR ?

• We had disabled an experiment feature for Akeyless secrets integration in CI pipelines
• Now, we need to remove the dead code associated with this feature and this MR deals with that
• the corresponding cleanup MR in Rails that removes the feature is merged and deployed

What does this MR do?

• Remove code related to the disabled Akeyless integration feature.