Allow for fd closing delay in connections test (#2687)

tests/connections.py

@@ -22,11 +22,15 @@ class AllConnectionsCreatedException(Exception):
     """
 
 
-def get_session_metrics(node):
+def get_session_metrics(node, timeout=3):
     with node.client() as c:
-        r = c.get("/node/metrics")
-        assert r.status_code == http.HTTPStatus.OK, r.status_code
-        return r.body.json()["sessions"]
+        end_time = time.time() + timeout
+        while time.time() < end_time:
+            r = c.get("/node/metrics")
+            if r.status_code == http.HTTPStatus.OK:
+                return r.body.json()["sessions"]
+            time.sleep(0.1)
+        assert r.status_code == http.HTTPStatus.OK, r
 
 
 def run(args):