Exit memory monitor with the same exit code as subprocess (#3222)

### Changes

- memory monitor should exit with the same exit code as subprocess run
for measurements

### Reason for changes

- we got some issues in validation, where convert-cli failed and
pipelines still passed, as memory_monitor returned with exit code 0

### Related tickets

161453

Author: wkobielx

tools/memory_monitor.py

@@ -13,6 +13,7 @@
 import logging
 import queue
 import subprocess
+import sys
 import threading
 import time
 from enum import Enum
@@ -362,6 +363,7 @@ def _subtract_first_element(data):
 
     with subprocess.Popen(" ".join(args.executable), shell=True) as p:
         p.wait()
+        exit_code = p.returncode
 
         # Stop addition of new values as soon as possible
         for mm in memory_monitors:
@@ -380,3 +382,5 @@ def _subtract_first_element(data):
             summary_data.append([mm.memory_type.value, fz, f"{int(max(memory_values))} {mm.memory_unit.value}"])
     print("\nMemory summary:")
     print(tabulate(summary_data, headers=["Memory type", "From zero", "Peak value"]))
+
+    sys.exit(exit_code)