tests: Removes outdated marketplace download test (#20454)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/tests/unit_tests/core/helper/test_marketplace.py

@@ -1,7 +0,0 @@
-from core.helper.marketplace import download_plugin_pkg
-
-
-def test_download_plugin_pkg():
-    pkg = download_plugin_pkg("langgenius/bing:0.0.1@e58735424d2104f208c2bd683c5142e0332045b425927067acf432b26f3d970b")
-    assert pkg is not None
-    assert len(pkg) > 0