feat(database): add noop mode with config flag and update related tests (#9054)

* test: enhance agent component tests and add new fixture for database-less sessions

- Added `use_noop_session` fixture to facilitate testing without a database.
- Expanded `TestAgentComponent` with new tests for agent responses using the Calculator tool and validation across all OpenAI and Anthropic models.
- Updated `test_component.py` to include tests for message sending without a database, ensuring proper event handling and message integrity.
- Refactored existing tests for clarity and consistency.

* fix: enhance user retrieval logic in get_or_create_super_user and teardown_superuser functions

- Updated user retrieval in both functions to handle different result types from the database query, ensuring robustness against unexpected return values.
- Added checks for `first()` method and list type to improve error handling and maintainability.

* feat: add support for no-op database operations in settings

- Introduced `use_noop_database` configuration option to disable all database operations, controlled by the `LANGFLOW_USE_NOOP_DATABASE` environment variable.
- Updated the `use_noop_session` fixture to reflect the new environment variable for testing without a database.

* feat: implement NoopSession for database-less operations

- Added NoopSession class to provide a no-operation database session, allowing for testing and operation without a real database connection.
- Updated DatabaseService to utilize NoopSession when the `use_noop_database` setting is enabled, ensuring all database operations are disabled in this mode.
- Enhanced error handling and logging for session management, improving robustness in scenarios where the database is not in use.

* refactor: update import paths for NoopSession in test files

- Changed import path for NoopSession from `langflow.services.database.service` to `langflow.services.database.session` in both `test_agent_component.py` and `test_component.py`.
- This refactor improves code organization and aligns with recent changes in the project structure.

* feat: enhance NoopSession with result handling methods

- Added an internal _NoopResult class to the NoopSession, providing methods `first()`, `all()`, and `one_or_none()` for better handling of no-operation results.
- This enhancement improves the usability of NoopSession in testing scenarios by mimicking expected database query behaviors.

* refactor: improve logging for NOOP database session

- Changed the log level from warning to info for the NOOP database session message in the DatabaseService class.
- This adjustment enhances clarity in logging, indicating that all DB operations are disabled without implying an error condition.

* docs: improve docstring formatting for custom_component_update function

- Reformatted the docstring for the custom_component_update function to enhance readability by breaking long lines into multiple lines.
- This change improves documentation clarity, making it easier for developers to understand the function's purpose and behavior.

* docs: add LANGFLOW_USE_NOOP_DATABASE environment variable documentation

- Introduced documentation for the new LANGFLOW_USE_NOOP_DATABASE environment variable, which allows users to enable a no-op database mode, avoiding database connections and operations.
- This addition enhances the clarity of configuration options available for Langflow, aiding users in understanding how to run flows without a database.

* refactor: move NOOP database session logging to settings

- Removed the logging statement from the DatabaseService class and added it to the `set_use_noop_database` field validator in the Settings class.
- This change centralizes the logging for the NOOP database session, improving code organization and ensuring that the message is logged whenever the setting is applied.

src/backend/tests/conftest.py

@@ -76,6 +76,10 @@ def blockbuster(request):
                 .can_block_in("rich/traceback.py", "_render_stack")
                 .can_block_in("langchain_core/_api/internal.py", "is_caller_internal")
                 .can_block_in("langchain_core/runnables/utils.py", "get_function_nonlocals")
+                .can_block_in("alembic/versions", "_load_revisions")
+                .can_block_in("dotenv/main.py", "find_dotenv")
+                .can_block_in("alembic/script/base.py", "_load_revisions")
+                .can_block_in("alembic/env.py", "_do_run_migrations")
             )
 
             for func in ["os.stat", "os.path.abspath", "os.scandir", "os.listdir"]:
@@ -366,6 +370,16 @@ def deactivate_tracing(monkeypatch):
     monkeypatch.undo()
 
 
+@pytest.fixture
+def use_noop_session(monkeypatch):
+    monkeypatch.setenv("LANGFLOW_USE_NOOP_DATABASE", "1")
+    # Optionally patch the Settings object if needed
+    # from langflow.services.settings.base import Settings
+    # monkeypatch.setattr(Settings, "use_noop_database", True)
+    yield
+    monkeypatch.undo()
+
+
 @pytest.fixture(name="client")
 async def client_fixture(
     session: Session,  # noqa: ARG001