Filter resource_tracker warnings in integration tests

Python 3.14+ emits multiprocessing resource_tracker warnings about
leaked semaphores during test subprocess cleanup. These warnings appear
in stderr and cause test assertions to fail. Filter them out the same
way we already filter DeprecationWarnings.

Fixes integration test failures on Python 3.14.

Author: przadka

test/integration/helpers.py

@@ -368,7 +368,15 @@ def print_json_indented(value):
 
 
 def remove_warnings(text):
-    return linesep.join(line for line in text.split(linesep) if 'DeprecationWarning' not in line)
+    """Filter out Python warnings from command output."""
+    return linesep.join(
+        line
+        for line in text.split(linesep)
+        if 'DeprecationWarning' not in line
+        and 'resource_tracker' not in line  # Python 3.14+ multiprocessing warnings
+        and 'UserWarning' not in line  # Python 3.14+ shows more warning details
+        and 'warnings.warn(' not in line  # Python 3.14+ shows source line in warnings
+    )
 
 
 class StringReader: