[INTERNAL] ui5-test-runner: Use --start option and remove unused dependency (#264)

The --start option is new and allows us to have one less dependency.
Also, --port 8081 is only useful for some minimal test monitoring and
hence more confusing than of actual use, as mentioned by Arnaud at:
SAP-samples/ui5-typescript-helloworld#31 (comment)

Author: akudev