improvement(stress): Report two lines of the error, instead of only 1…

…00 characters

Fixes #8291

sdcm/stress/base.py

@@ -151,5 +151,7 @@ def format_stress_cmd_error(exc: Exception) -> str:
     """Format nicely the exception from a stress command failure."""
 
     if hasattr(exc, "result") and exc.result.failed:
-        return f"Stress command completed with bad status {exc.result.exited}: {exc.result.stderr:.100}"
+        # Report only first two lines
+        message = "\n".join(exc.result.stderr.splitlines()[:2])
+        return f"Stress command completed with bad status {exc.result.exited}: {message}"
     return f"Stress command execution failed with: {exc}"