Make servers fixture in pytest module-wide

The servers are setup and torn down once per each test module. All the
logs and server state persists between individual tests within the same
module. The servers fixture representing these servers should be
module-wide as well.

(cherry picked from commit a72ff9fd57)

bin/tests/system/conftest.py

@@ -669,7 +669,7 @@ def system_test(
         request.node.stash[FIXTURE_OK] = True
 
 
-@pytest.fixture
+@pytest.fixture(scope="module")
 def servers(system_test_dir):
     instances = {}
     for entry in system_test_dir.rglob("*"):