[BUG] python UDF tests are leaking

[revans2]

Describe the bug
As a part of trying to debug host memory usage I found that the UDF tests are leaking badly. Specifically udf_test.py and udf_cudf_test.py

Steps/Code to reproduce bug
Build the plugin and run some of the tests in there with -Dai.rapids.refcount.debug=true then look at the results of what happens.

For example:

PYSP_TEST_spark_master='local[1]' COVERAGE_SUBMIT_FLAGS=-Dai.rapids.refcount.debug=true TEST_PARALLEL=0 SPARK_HOME=$HOME/src/spark_3.2.0/ ./run_pyspark_from_build.sh -k 'udf_test.py and test_group_agg and not more_typesregate_udf and Byte and not more_types' -s 2>&1 | tee single_udf.txt

Showed that 48 column vectors were leaked and one host buffer was leaked. This is just one test, there are 137 tests in those two files and when I run all of them I see over 20,615 items being leaked.

Expected behavior
There are no items that are leaked.