Split up "run-tests"

[aweingarten]

Currently the pipelines log reads like a firehose. Its a LOT. Thinking that it could be made much more navigable if we break the run-tests task [here (https://github.com/acquia/blt/blob/8.x/scripts/pipelines/acquia-pipelines.yml#L26) into 2-3 targets

        - run-tests:
            type: script
            script:
              - source ${BLT_DIR}/scripts/pipelines/run_tests

like:

• prep
• code linting
• automated testing

That way you have clickable expandable regions that get you to the information you need as opposed to a single column of text!

[grasmash]

Addressed in #1544.