test: actually exercise the depth cap in fails-closed test

The previous fixture stored the leaf under the secret-named key
'aws_web_identity_token', which the recursor's key-name short-circuit
redacts regardless of the cap — so the test passed both with and
without the cap in place. Empirically confirmed: under an uncapped
mutant the old fixture still hides the secret (key-name catches it),
the new fixture leaks it (only the cap can stop it). Swap the leaf
key to a non-secret name so the cap is the only redaction path
exercised, making the test fail on mutation as advertised.

tests/test_litellm/proxy/proxy_server/test_routes_config.py

@@ -360,11 +360,11 @@ def test_redact_secret_values_in_obj_fails_closed_at_max_depth():
     branch to fail-open would surface here."""
     from litellm.proxy import proxy_server as ps
 
-    # build a non-secret-keyed wrap chain deeper than the cap, with a real
-    # secret at the bottom. Using a non-secret key ("wrap") forces the
-    # recursor down the recursion branch instead of short-circuiting on the
-    # key name itself.
-    nested: object = {"aws_web_identity_token": "sk-leak-bottom"}
+    # leaf and wrap keys are both NON-secret so neither the key-name
+    # short-circuit nor the explicit-secret set catches the leak. The cap is
+    # the only thing standing between the secret and the response — flip the
+    # cap to fail-open and the secret comes back verbatim.
+    nested: object = {"notes": "sk-leak-bottom"}
     for _ in range(ps._REDACT_SECRET_MAX_DEPTH + 2):
         nested = {"wrap": nested}