Make selective jobs run in parallel

- Add separate *-selective-parallel jobs. Existing *-selective jobs
will continue to be non-parallel
- When QA_TESTS has files included (_spec), use non-parallel selective
jobs.
- When QA_TESTS has folders included, use use parallel selective jobs
by setting KNAPSACK_TEST_FILE_PATTERN.
- Create knapsack reports for *-selective-parallel jobs from existing
jobs to avoid falling back to master_report.json resulting in better
parallelisation.