Revert .init to .new.tap for Jenkins Service

What does this MR do?

Fixes a bug introduced in this MR where .new.tap was replace with .init but the Service::DockerRun::Jenkins class does not inherit from QA::Resource::Base where the change was made.

The test did not fail in the original MR as it was quarantined. Here is a manual run that failed: https://gitlab.com/gitlab-org/gitlab-qa-mirror/-/jobs/1372698381#L13898

Conformity

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• This change is backwards compatible across updates, or this does not apply.