[SPARK-25306][SQL][FOLLOWUP] Change test to ignore in FilterPushdownBenchmark

## What changes were proposed in this pull request?

This is a follow-up of apache#22313 and aim to ignore the micro benchmark test which takes over 2 minutes in Jenkins.
- https://amplab.cs.berkeley.edu/jenkins/view/Spark%20QA%20Test%20(Dashboard)/job/spark-master-test-sbt-hadoop-2.6/4939/consoleFull

## How was this patch tested?

The test case should be ignored in Jenkins.
```
[info] FilterPushdownBenchmark:
...
[info] - Pushdown benchmark with many filters !!! IGNORED !!!
```

Closes apache#22336 from dongjoon-hyun/SPARK-25306-2.

Authored-by: Dongjoon Hyun <[email protected]>
Signed-off-by: Xiao Li <[email protected]>

Author: dongjoon-hyun

sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/FilterPushdownBenchmark.scala

@@ -399,7 +399,7 @@ class FilterPushdownBenchmark extends SparkFunSuite with BenchmarkBeforeAndAfter
     }
   }
 
-  test(s"Pushdown benchmark with many filters") {
+  ignore(s"Pushdown benchmark with many filters") {
     val numRows = 1
     val width = 500