Add 'with runner' context to pipeline data_builder

What does this MR do?

Adds a context to the pipeline DataBuilder test. The DataBuilder is used to generate JSON data for webhooks. When there is no runner the runner field should be nil and if there is a runner it should contain runner data. The code that will be tested can be found in lib/gitlab/data_builder/pipeline.rb#L66

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done