Pass a "d7" parameter into scripts/test-only.sh and discard scripts/test-only-d7.sh

Migrated issue

Reported by: jonathan1055

Related to !400 (merged)

Problem/Motivation

The scripts test-only.sh and test-only-d7.sh are very similar. Maintaining them both is tedious. We can pass in a "d7" parameter and consolidate the processing in one script.

We do not need to worry about BC becuase these are internal files, no customised d7 pipeline should be using them directly.