[SPARK-28270][TEST-MAVEN][FOLLOW-UP][SQL][PYTHON][TESTS] Avoid cast input of UDF as double in the failed test in udf-aggregate_part1.sql

## What changes were proposed in this pull request?

It still can be flaky on certain environments due to float limitation described at apache#25110 . See apache#25110 (comment)

- https://amplab.cs.berkeley.edu/jenkins/view/Spark%20QA%20Test%20(Dashboard)/job/spark-master-test-maven-hadoop-2.7/6584/testReport/org.apache.spark.sql/SQLQueryTestSuite/udf_pgSQL_udf_aggregates_part1_sql___Regular_Python_UDF/

```
Expected "700000000000[6] 1", but got "700000000000[5] 1" Result did not match for query apache-spark-on-k8s#33
SELECT CAST(avg(udf(CAST(x AS DOUBLE))) AS long), CAST(udf(var_pop(CAST(x AS DOUBLE))) AS decimal(10,3))
FROM (VALUES (7000000000005), (7000000000007)) v(x)
```

Here;s what's going on: apache#25110 (comment)

```
scala> Seq("7000000000004.999", "7000000000006.999").toDF().selectExpr("CAST(avg(value) AS long)").show()
+--------------------------+
|CAST(avg(value) AS BIGINT)|
+--------------------------+
|             7000000000005|
+--------------------------+
```

Therefore, this PR just avoid to cast in the specific test.

This is a temp fix. We need more robust way to avoid such cases.

## How was this patch tested?

It passes with Maven in my local before/after this PR. I believe the problem seems similarly the Python or OS installed in the machine. I should test this against PR builder with `test-maven` for sure..

Closes apache#25128 from HyukjinKwon/SPARK-28270-2.

Authored-by: HyukjinKwon <[email protected]>
Signed-off-by: HyukjinKwon <[email protected]>

Author: HyukjinKwon

sql/core/src/test/resources/sql-tests/inputs/udf/pgSQL/udf-aggregates_part1.sql

@@ -78,7 +78,7 @@ FROM (VALUES ('-Infinity'), ('Infinity')) v(x);
 -- test accuracy with a large input offset
 SELECT CAST(avg(udf(CAST(x AS DOUBLE))) AS int), CAST(udf(var_pop(CAST(x AS DOUBLE))) AS decimal(10,3))
 FROM (VALUES (100000003), (100000004), (100000006), (100000007)) v(x);
-SELECT CAST(avg(udf(CAST(x AS DOUBLE))) AS long), CAST(udf(var_pop(CAST(x AS DOUBLE))) AS decimal(10,3))
+SELECT CAST(avg(udf(x)) AS long), CAST(udf(var_pop(CAST(x AS DOUBLE))) AS decimal(10,3))
 FROM (VALUES (7000000000005), (7000000000007)) v(x);
 
 -- SQL2003 binary aggregates [SPARK-23907]

sql/core/src/test/resources/sql-tests/results/udf/pgSQL/udf-aggregates_part1.sql.out

@@ -271,10 +271,10 @@ struct<CAST(avg(CAST(udf(cast(x as double)) AS DOUBLE)) AS INT):int,CAST(udf(var
 
 
 -- !query 33
-SELECT CAST(avg(udf(CAST(x AS DOUBLE))) AS long), CAST(udf(var_pop(CAST(x AS DOUBLE))) AS decimal(10,3))
+SELECT CAST(avg(udf(x)) AS long), CAST(udf(var_pop(CAST(x AS DOUBLE))) AS decimal(10,3))
 FROM (VALUES (7000000000005), (7000000000007)) v(x)
 -- !query 33 schema
-struct<CAST(avg(CAST(udf(cast(x as double)) AS DOUBLE)) AS BIGINT):bigint,CAST(udf(var_pop(cast(x as double))) AS DECIMAL(10,3)):decimal(10,3)>
+struct<CAST(avg(CAST(udf(x) AS DOUBLE)) AS BIGINT):bigint,CAST(udf(var_pop(cast(x as double))) AS DECIMAL(10,3)):decimal(10,3)>
 -- !query 33 output
 7000000000006	1