fix: revert SystemExit re-raise in run_mapper fixture #241

Job	Run time
Architecture & Import Contracts	31s
Lint & Type Check	38s
Mutation Testing	54s
Pre-commit hooks	56s
Complexity & Maintainability Analysis	12s
test (ubuntu-latest, 3.10)	2m 46s
test (ubuntu-latest, 3.13)	2m 46s
test (ubuntu-latest, 3.11)	2m 31s
test (ubuntu-latest, 3.12)	2m 49s
test (macos-latest, 3.11)	5m 11s
test (macos-latest, 3.13)	7m 28s
test (windows-latest, 3.11)	16m 59s
test (windows-latest, 3.13)	19m 3s
test (windows-latest, 3.12)	15m 48s
test (macos-latest, 3.12)	5m 8s
test (macos-latest, 3.10)	7m 54s
test (windows-latest, 3.10)	18m 50s
	1h 50m 24s

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