[SPARK-32850][TEST][FOLLOWUP] Fix flaky test due to timeout

### What changes were proposed in this pull request?

Increase test timeout.

### Why are the changes needed?

It's more reasonable to use 60s instead of 6s since many code place use the 60s in `TestUtils.waitUntilExecutorsUp`.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass exists test.

Closes #31166 from ulysses-you/SPARK-32850-FOLLOWUP.

Authored-by: ulysses-you <ulyssesyou18@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
(cherry picked from commit f64297d)
Signed-off-by: HyukjinKwon <gurwls223@apache.org>

core/src/test/scala/org/apache/spark/storage/BlockManagerDecommissionIntegrationSuite.scala

@@ -49,7 +49,7 @@ class BlockManagerDecommissionIntegrationSuite extends SparkFunSuite with LocalS
         .set(config.DECOMMISSION_ENABLED, true)
         .set(config.STORAGE_DECOMMISSION_ENABLED, isEnabled)
       sc = new SparkContext(conf)
-      TestUtils.waitUntilExecutorsUp(sc, 2, 6000)
+      TestUtils.waitUntilExecutorsUp(sc, 2, 60000)
       val executors = sc.getExecutorIds().toArray
       val decommissionListener = new SparkListener {
         override def onTaskStart(taskStart: SparkListenerTaskStart): Unit = {