[trace][bugfix] Fix possible circular import for trace util (#2803)

# Description

Make an import locally to avoid circular import.

# All Promptflow Contribution checklist:
- [x] **The pull request does not introduce [breaking changes].**
- [ ] **CHANGELOG is updated for new features, bug fixes or other
significant changes.**
- [x] **I have read the [contribution guidelines](../CONTRIBUTING.md).**
- [ ] **Create an issue and link to the pull request to get dedicated
review from promptflow team. Learn more: [suggested
workflow](../CONTRIBUTING.md#suggested-workflow).**

## General Guidelines and Best Practices
- [x] Title of the pull request is clear and informative.
- [x] There are a small number of commits, each of which have an
informative message. This means that previously merged commits do not
appear in the history of the PR. For more information on cleaning up the
commits in your PR, [see this
page](https://github.com/Azure/azure-powershell/blob/master/documentation/development-docs/cleaning-up-commits.md).

### Testing Guidelines
- [x] Pull request includes test coverage for the included changes.

src/promptflow-devkit/promptflow/_sdk/_orm/session.py

@@ -14,7 +14,6 @@
 from sqlalchemy.orm import Session, sessionmaker
 from sqlalchemy.schema import CreateTable
 
-from promptflow._sdk._configuration import Configuration
 from promptflow._sdk._constants import (
     CONNECTION_TABLE_NAME,
     EVENT_TABLENAME,
@@ -90,6 +89,7 @@ def mgmt_db_session() -> Session:
         engine = create_engine(f"sqlite:///{str(LOCAL_MGMT_DB_PATH)}?check_same_thread=False", future=True)
         engine = support_transaction(engine)
 
+        from promptflow._sdk._configuration import Configuration
         from promptflow._sdk._orm import Connection, Experiment, ExperimentNodeRun, Orchestrator, RunInfo
 
         create_or_update_table(engine, orm_class=RunInfo, tablename=RUN_INFO_TABLENAME)

src/promptflow-devkit/promptflow/_sdk/_utils.py

@@ -64,8 +64,6 @@
     UnsecureConnectionError,
 )
 from promptflow._sdk._vendor import IgnoreFile, get_ignore_file, get_upload_files_from_folder
-from promptflow._sdk.entities._flows.base import FlowBase
-from promptflow._sdk.entities._flows.dag import Flow as DAGFlow
 from promptflow._utils.flow_utils import is_flex_flow, resolve_flow_path
 from promptflow._utils.logger_utils import get_cli_sdk_logger
 from promptflow._utils.user_agent_utils import ClientUserAgentUtil
@@ -1077,10 +1075,13 @@ def is_flex_run(run: "Run") -> bool:
 update_dict_value_with_connections = update_dict_value_with_connections
 
 
-def get_flow_name(flow: Union[FlowBase, Path]) -> str:
+def get_flow_name(flow) -> str:
     if isinstance(flow, Path):
         return flow.resolve().name
+
+    from promptflow._sdk.entities._flows.dag import Flow as DAGFlow
+
     if isinstance(flow, DAGFlow):
         return flow.name
-    # others: flex flow, prompty, etc.
+    # should be promptflow._sdk.entities._flows.base.FlowBase: flex flow, prompty, etc.
     return flow.code.name