Run the integration tests from the current branch
    
    Previously, the integration test pipeline was configured to always use the tests present on the
    master branch. When running the pre-merge pipeline for a PR, this would result in potentially
    out-dated tests being run. This change runs the tests from the current branch, allowing the code
    and the tests to evolve together.
    
    This also disables the default checkout of the master branch, which is unnecessary when calling
    checkout() from the pipeline.