Remove service proxy test helper

[pablochacin]

Description

The service proxy test helper was introduced to facilitate access to services in e2e tests without having to expose them in the cluster. Since #160 e2e tests use ingresses for accessing services, making the service proxy redundant.

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works.
• I have run linter locally (make lint) and all checks pass.
• I have run tests locally (make test) and all tests pass.
• I have run relevant e2e test locally (make e2e-xxx for agent, disruptors, kubernetes or cluster related changes)
• Any dependent changes have been merged and published in downstream modules