Look for extra__ instead of extra_ in get_field (#27489)

This reduces likelihood of false positive.  It's not possible as currently used.  But if someone were to add an extra field `extra_info` for example, that would cause trouble avoided by this change.

airflow/providers/grpc/hooks/grpc.py

@@ -150,7 +150,7 @@ def run(
     def _get_field(self, field_name: str):
         """Get field from extra, first checking short name, then for backcompat we check for prefixed name."""
         backcompat_prefix = "extra__grpc__"
-        if field_name.startswith("extra_"):
+        if field_name.startswith("extra__"):
             raise ValueError(
                 f"Got prefixed name {field_name}; please remove the '{backcompat_prefix}' prefix "
                 "when using this method."

airflow/providers/jdbc/hooks/jdbc.py

@@ -63,7 +63,7 @@ def get_ui_field_behaviour() -> dict[str, Any]:
     def _get_field(self, extras: dict, field_name: str):
         """Get field from extra, first checking short name, then for backcompat we check for prefixed name."""
         backcompat_prefix = "extra__jdbc__"
-        if field_name.startswith("extra_"):
+        if field_name.startswith("extra__"):
             raise ValueError(
                 f"Got prefixed name {field_name}; please remove the '{backcompat_prefix}' prefix "
                 "when using this method."

airflow/providers/microsoft/azure/hooks/wasb.py

@@ -149,7 +149,7 @@ def __init__(
 
     def _get_field(self, extra_dict, field_name):
         prefix = "extra__wasb__"
-        if field_name.startswith("extra_"):
+        if field_name.startswith("extra__"):
             raise ValueError(
                 f"Got prefixed name {field_name}; please remove the '{prefix}' prefix "
                 f"when using this method."