TestKit backend output goes to stdout/stderr (#1084)

From there, TestKit can pick it up and write it into logfiles if desired.
neo4j-drivers/testkit#309

Author: robsdedude

testkit/backend.py

@@ -3,12 +3,15 @@
 Assumes driver and backend has been built.
 Responsible for starting the test backend.
 """
-import os, subprocess
+import os
+import subprocess
+import sys
 
 
 if __name__ == "__main__":
-    err = open("/artifacts/backenderr.log", "w")
-    out = open("/artifacts/backendout.log", "w")
     subprocess.check_call(
-        ["java", "-jar", "testkit-backend/target/testkit-backend.jar", os.getenv('TEST_BACKEND_SERVER', '')], stdout=out, stderr=err)
+        ["java", "-jar", "testkit-backend/target/testkit-backend.jar",
+        os.getenv('TEST_BACKEND_SERVER', '')],
+        stdout=sys.stdout, stderr=sys.stderr
+    )