Improve python scripts for parquet to delta conversion

`from package_name import *` is considered a [bad coding practice](https://docs.python.org/3/tutorial/modules.html#more-on-modules) in python, because it may import unneeded classes and obstructs static code analysis.

Author: LoHertel

articles/synapse-analytics/sql/query-delta-lake-format.md

@@ -49,7 +49,7 @@ If you don't have this subfolder, you are not using Delta Lake format. You can c
 
 ```python
 %%pyspark
-from delta.tables import *
+from delta.tables import DeltaTable
 deltaTable = DeltaTable.convertToDelta(spark, "parquet.`abfss://[email protected]/covid`")
 ```
 
@@ -168,7 +168,7 @@ If you don't have this subfolder, you are not using Delta Lake format. You can c
 
 ```python
 %%pyspark
-from delta.tables import *
+from delta.tables import DeltaTable
 deltaTable = DeltaTable.convertToDelta(spark, "parquet.`abfss://[email protected]/yellow`", "year INT, month INT")
 ```