[Bugfix] Remove faulty test for oot attention backend (#22286)

Signed-off-by: mgoin <mgoin64@gmail.com>

tests/plugins_tests/test_platform_plugins.py

@@ -4,9 +4,7 @@
 import pytest
 import torch
 
-from vllm.attention.selector import get_attn_backend
 from vllm.plugins import load_general_plugins
-from vllm.utils import STR_BACKEND_ENV_VAR, STR_INVALID_VAL
 
 
 def test_platform_plugins():
@@ -27,14 +25,6 @@ def test_platform_plugins():
         f" is loaded. The first import:\n{_init_trace}")
 
 
-def test_oot_attention_backend(monkeypatch: pytest.MonkeyPatch):
-    # ignore the backend env variable if it is set
-    with monkeypatch.context() as m:
-        m.setenv(STR_BACKEND_ENV_VAR, STR_INVALID_VAL)
-        backend = get_attn_backend(16, torch.float16, "auto", 16, False)
-        assert backend.get_name() == "Dummy_Backend"
-
-
 def test_oot_custom_op(monkeypatch: pytest.MonkeyPatch):
     # simulate workload by running an example
     load_general_plugins()