Outcome analysis: complain about repeated configuration name

[gilles-peskine-arm]

analyze_outcomes.py should complain if the same test run identification (platform, configuration, test suite, test case) appears more than once in outcomes.csv. That would likely be caused by having a test script that tests multiple configurations, but doesn't give them different configuration names (the default configuration name is the all.sh component name). This has happened, e.g. #7290.