[SPARK-35836][SHUFFLE][CORE] Removed the reference to spark.shuffle.push.based.enabled in ShuffleBlockPusherSuite

### What changes were proposed in this pull request?
It is a trivial change to remove the reference to an incorrect configuration for push-based shuffle from a test suite.
Ref: #30312
With SPARK-32917, `ShuffleBlockPusher` and its test suite was introduced. `ShuffleBlockPusher` is created only when push-based shuffle is enabled and the tests in `ShuffleBlockPusherSuite` are just testing the functionality in the pusher. So there is no need to have these configs enabled in these test.

### Why are the changes needed?
This change removes an incorrect configuration from the test suite.

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
This change just removes an incorrect configuration from the test suite so haven't added any UTs for it.

Closes #32992 from otterc/SPARK-35836.

Authored-by: Chandni Singh <[email protected]>
Signed-off-by: Mridul Muralidharan <mridul<at>gmail.com>

Author: otterc

core/src/test/scala/org/apache/spark/shuffle/ShuffleBlockPusherSuite.scala

@@ -56,8 +56,6 @@ class ShuffleBlockPusherSuite extends SparkFunSuite with BeforeAndAfterEach {
     when(dependency.partitioner).thenReturn(new HashPartitioner(8))
     when(dependency.serializer).thenReturn(new JavaSerializer(conf))
     when(dependency.getMergerLocs).thenReturn(Seq(BlockManagerId("test-client", "test-client", 1)))
-    conf.set("spark.shuffle.push.based.enabled", "true")
-    conf.set("spark.shuffle.service.enabled", "true")
     // Set the env because the shuffler writer gets the shuffle client instance from the env.
     val mockEnv = mock(classOf[SparkEnv])
     when(mockEnv.conf).thenReturn(conf)