ci: fix collect multi-dut test case with markers issue

While collecting, we stop registering the new plugin.
Otherwise the new created plugin will override the one we passed

also run the tests inside idf. the behavior is different.

conftest.py

@@ -1,14 +1,13 @@
 # SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: Apache-2.0
 # pylint: disable=W0621  # redefined-outer-name
-
+#
 # IDF is using [pytest](https://github.com/pytest-dev/pytest) and
 # [pytest-embedded plugin](https://github.com/espressif/pytest-embedded) as its test framework.
-
+#
 # if you found any bug or have any question,
 # please report to https://github.com/espressif/pytest-embedded/issues
 # or discuss at https://github.com/espressif/pytest-embedded/discussions
-
 import os
 import sys
 
@@ -432,11 +431,12 @@ def pytest_configure(config: Config) -> None:
         for f in glob.glob(os.path.join(IDF_PATH, app_info_filepattern)):
             apps.extend(import_apps_from_txt(f))
 
-    config.stash[IDF_PYTEST_EMBEDDED_KEY] = IdfPytestEmbedded(
-        target=target,
-        apps=apps,
-    )
-    config.pluginmanager.register(config.stash[IDF_PYTEST_EMBEDDED_KEY])
+    if '--collect-only' not in config.invocation_params.args:
+        config.stash[IDF_PYTEST_EMBEDDED_KEY] = IdfPytestEmbedded(
+            target=target,
+            apps=apps,
+        )
+        config.pluginmanager.register(config.stash[IDF_PYTEST_EMBEDDED_KEY])
 
 
 def pytest_unconfigure(config: Config) -> None: