Testing: Don't split test suite for remote client tests

conftest.py

@@ -74,7 +74,9 @@ def pytest_collection_modifyitems(config, items):
     # This provides a more balanced partitioning of our test suite (in terms of
     # necessary time to run it) between the slow and fast slots we have on CIs.
     slow_items = []
-    if os.environ.get('CI'):
+    if os.environ.get("CI") and not os.environ.get(
+        "SPYDER_TEST_REMOTE_CLIENT"
+    ):
         slow_items = [
             item for item in items if 'test_mainwindow' in item.nodeid
         ]