remove log-cache-blackbox job

[mkocher]

The log-cache-blackbox job is a test job that is not being used any
more. Deleting for now, if it's important it will come back.

Description

Please include a summary of the change.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Testing performed?

• Unit tests
• Integration tests
• Acceptance tests

Checklist:

• This PR is being made against the main branch, or relevant version branch
• I have made corresponding changes to the documentation
• I have added testing for my changes

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. Unfortunately, the Pivotal Tracker project is private so you may be unable to view the contents of the story.

The labels on this github issue will be updated when the story is started.