Standardize test usage of context: Context across operator tests (avoid context=None)

### Description ### Title Standardize test usage of `context: Context` across operator tests (avoid `context=None`) --- ### Description Many operator tests across the Airflow codebase currently invoke `execute()` like this: related: https://github.com/apache/airflow/blob/main/providers/microsoft/azure/src/airflow/providers/microsoft/azure/operators/wasb_delete_blob.py https://github.com/apache/airflow/blob/main/providers/microsoft/azure/tests/unit/microsoft/azure/operators/test_wasb_delete_blob.py test code ```python operator.execute(None) ``` However, the `execute()` method is explicitly typed as: ```python def execute(self, context: Context) -> None: ``` To align with this contract and improve typing correctness and future maintainability, we should replace `None` with a minimal `Context` object (e.g., `{}` or `MagicMock(spec=Context)`). #### Benefits of this change: - Aligns test cases with actual method signature (`context: Context`) - Avoids potential mypy/type-checking issues (especially in Airflow 3+) - Prevents misleading behavior in tests by not passing `None` when `context` is required - Improves clarity and correctness in test expectations --- ### Suggested Migration Pattern **Before:** ```python operator.execute(None) ``` **After:** ```python if TYPE_CHECKING: try: from airflow.sdk.definitions.context import Context except ImportError: # TODO: Remove once provider drops support for Airflow 2 from airflow.utils.context import Context mock_context: Context = {} operator.execute(mock_context) ``` **Or (stricter typing):** ```python from unittest.mock import MagicMock if TYPE_CHECKING: try: from airflow.sdk.definitions.context import Context except ImportError: # TODO: Remove once provider drops support for Airflow 2 from airflow.utils.context import Context mock_context = MagicMock(spec=Context) operator.execute(mock_context) ``` ### Use case/motivation _No response_ ### Related issues _No re…