test: update tag-merge tests for default-deny client tag policy

Two pre-existing tests codified the pre-fix behavior where any caller-
supplied metadata.tags would flow through to spend logs and routing:

- test_add_key_or_team_level_spend_logs_metadata_to_request exercised
  the request/key/team tag merge. Set allow_client_tags=True on the key
  metadata so the merge path is still tested under the new regime.

- test_create_file_with_nested_litellm_metadata asserted that
  litellm_metadata[tags] form-data propagated to the handler. Drop the
  tag field; the test still proves nested form-parser correctness via
  spend_logs_metadata and environment.

tests/proxy_unit_tests/test_proxy_utils.py

@@ -162,9 +162,13 @@ async def test_add_key_or_team_level_spend_logs_metadata_to_request(
 
     print(f"team_sl_metadata: {team_sl_metadata}")
     mock_request.url.path = "/chat/completions"
+    # Opt the key into client-supplied tags so request_tags are preserved
+    # and merged with admin-configured key/team tags. Without this flag,
+    # request_tags would be stripped by add_litellm_data_to_request.
     key_metadata = {
         "tags": key_tags,
         "spend_logs_metadata": key_sl_metadata,
+        "allow_client_tags": True,
     }
     team_metadata = {
         "tags": team_tags,

tests/test_litellm/proxy/openai_files_endpoint/test_files_endpoint.py

@@ -1295,7 +1295,6 @@ def test_create_file_with_nested_litellm_metadata(
             "target_model_names": "gpt-3.5-turbo",
             "litellm_metadata[spend_logs_metadata][owner]": "john_doe",
             "litellm_metadata[spend_logs_metadata][team]": "engineering",
-            "litellm_metadata[tags]": "production",
             "litellm_metadata[environment]": "prod",
         },
         headers={"Authorization": "Bearer test-key"},
@@ -1306,11 +1305,12 @@ def test_create_file_with_nested_litellm_metadata(
     result = response.json()
     assert result["id"] == "file-test-123"
 
-    # Verify nested metadata was correctly parsed
+    # Verify nested metadata was correctly parsed.
+    # Note: caller-supplied `tags` is stripped by default; test removed
+    # to keep the parsing test focused on parser correctness.
     assert "spend_logs_metadata" in captured_litellm_metadata
     assert captured_litellm_metadata["spend_logs_metadata"]["owner"] == "john_doe"
     assert captured_litellm_metadata["spend_logs_metadata"]["team"] == "engineering"
-    assert captured_litellm_metadata["tags"] == "production"
     assert captured_litellm_metadata["environment"] == "prod"