Concurrent runs of the test suite fail

[viveklak]

Some resources seem to have fixed names which can collide if concurrent runs occur, e.g.:

aws:lb:TargetGroup (LBListenerTargetGroupF04FCF6D):
      error: 1 error occurred:
      	* error creating LB Target Group: DuplicateTargetGroupName: A target group with the same name 'LBListenerTargetGroupF04FCF6D' exists, but with different settings
      	status code: 400, request id: 7e4ad2d9-bb3b-4f45-aa1f-507f8355a098

For the time being concurrency has been dropped to 1 here: ad5922e.

We should revisit if autonaming can be safely honored on resources corresponding to the L1 CDK constructs to make this moot.

[jkisk]

making a test comment to validate that we have fixed #50

[corymhall]

This has been fixed in some previous work.