Set default pipeline to benchmark-only

[IanHoang]

Is your feature request related to a problem? Please describe.

A good majority of users use OSB to benchmark pre-existing clusters.

Describe the solution you'd like

We should set the default to use benchmark-only pipeline.

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.

[cgchinmay]

@IanHoang Would like to work on this issue