Refactor glue to iceberg table conversion (#2660)

# Rationale for this change
 Note: Opening this to verify auto-run CI behavior.

This also includes a small refactor to `_convert_glue_to_iceberg`. We
were assigning parameters early and never using it. Since we only need
specific values from Parameters, this change uses the walrus operator to
read them inline and removes the unused variable.

## Are these changes tested?
Yes

## Are there any user-facing changes?
No

Author: geruh

pyiceberg/catalog/glue.py

@@ -355,34 +355,29 @@ def __init__(self, name: str, client: Optional["GlueClient"] = None, **propertie
                 _register_glue_catalog_id_with_glue_client(self.glue, glue_catalog_id)
 
     def _convert_glue_to_iceberg(self, glue_table: "TableTypeDef") -> Table:
-        properties: Properties = glue_table["Parameters"]
-
-        database_name = glue_table.get("DatabaseName", None)
-        if database_name is None:
+        if (database_name := glue_table.get("DatabaseName")) is None:
             raise ValueError("Glue table is missing DatabaseName property")
 
-        parameters = glue_table.get("Parameters", None)
-        if parameters is None:
-            raise ValueError("Glue table is missing Parameters property")
+        if (table_name := glue_table.get("Name")) is None:
+            raise ValueError("Glue table is missing Name property")
 
-        table_name = glue_table["Name"]
+        if (parameters := glue_table.get("Parameters")) is None:
+            raise ValueError("Glue table is missing Parameters property")
 
-        if TABLE_TYPE not in properties:
+        if (glue_table_type := parameters.get(TABLE_TYPE)) is None:
             raise NoSuchPropertyException(
                 f"Property {TABLE_TYPE} missing, could not determine type: {database_name}.{table_name}"
             )
-        glue_table_type = properties[TABLE_TYPE]
 
         if glue_table_type.lower() != ICEBERG:
             raise NoSuchIcebergTableError(
                 f"Property table_type is {glue_table_type}, expected {ICEBERG}: {database_name}.{table_name}"
             )
 
-        if METADATA_LOCATION not in properties:
+        if (metadata_location := parameters.get(METADATA_LOCATION)) is None:
             raise NoSuchPropertyException(
                 f"Table property {METADATA_LOCATION} is missing, cannot find metadata for: {database_name}.{table_name}"
             )
-        metadata_location = properties[METADATA_LOCATION]
 
         io = self._load_file_io(location=metadata_location)
         file = io.new_input(metadata_location)