Remove the Scala function version of regexp_extract_all

SPARK-24884 implement regexp_extract_all and added the scala function version of it.
According https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/functions.scala#L41-L59, it seems good for remove the scala function version. Although I think is regexp_extract_all is very useful, if we just reference the description.