remove unwanted code

Author: TheAnshul756

instrumentation/opentelemetry-instrumentation-django/tests/views.py

@@ -82,10 +82,3 @@ async def async_with_custom_header(request):
     response.headers["custom-test-header-1"] = "test-header-value-1"
     response.headers["custom-test-header-2"] = "test-header-value-2"
     return response
-
-class DummyMiddleware:
-    def __init__(self, get_response):
-        self.get_response = get_response
-
-    def __call__(self, request):
-        return self.get_response(request)