Fix `updateTableStats` to update table stats always with new stats or None

system shall update the table stats automatically if user set spark.sql.statistics.size.autoUpdate.enabled as true, currently this property is not having any significance even if it is enabled or disabled. This feature is similar to Hives auto-gather feature where statistics are automatically computed by default if this feature is enabled.

Reference:

https://cwiki.apache.org/confluence/display/Hive/StatsDev

Reproducing steps:

scala> spark.sql("create table table1 (name string,age int) stored as parquet")

scala> spark.sql("insert into table1 select 'a',29")
res2: org.apache.spark.sql.DataFrame = []

scala> spark.sql("desc extended table1").show(false)
---------------------------------------------------------------------------------------++------

---------------------------------------------------------------------------------------++------

---------------------------------------------------------------------------------------++------