Backstop tests not working as expected for LLCSSBG & LRC tests when run generally

[jeawhanlee]

Is your feature request related to a problem? Please describe.
Backstop tests will not run as expected for llcssbg & lrc tests when run generally because the backstop reference is generated.

Describe the solution you'd like
Reworking the way we detect the valid lists of scenario URLs for reference generation should solve this issue

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.