Remove USE_CDP_HIVE=false and associated code

We recently moved to use USE_CDP_HIVE=true by default, and Impala 4 intends to remove the CDH / Hive 2 code. We do not want to incur the overhead of maintaining this old support. This Jira tracks removing that code.

USE_CDP_HIVE should be removed entirely, and the code should be the equivalent of what USE_CDP_HIVE=true is now.