Python: CG trace: Handle SystemExit

otherwise, with-exit would end the tracer without producing any output :|

python/tools/recorded-call-graph-metrics/example/with-exit.py

@@ -0,0 +1,5 @@
+import sys
+
+print("will exit now")
+
+sys.exit()

python/tools/recorded-call-graph-metrics/src/cg_trace/tracer.py

@@ -173,12 +173,15 @@ class CallGraphTracer:
         try:
             sys.setprofile(self.profilefunc)
             exec(code, globals, locals)
-            sys.setprofile(None)
             return "completed"
+        except SystemExit:
+            return "completed (SystemExit)"
         except Exception:
             sys.setprofile(None)
             LOGGER.info("Exception occurred while running program:", exc_info=True)
             return "exception occurred"
+        finally:
+            sys.setprofile(None)
 
     def profilefunc(self, frame: FrameType, event: str, arg):
         # ignore everything until the first call, since that is `exec` from the `run`