[HOTFIX] [SQL] Fixes compilation error

Jenkins master builders are currently broken by a merge conflict between PR #8584 and PR #8155.

Author: Cheng Lian <lian@databricks.com>

Closes #8614 from liancheng/hotfix/fix-pr-8155-8584-conflict.

sql/core/src/test/scala/org/apache/spark/sql/SQLConfSuite.scala

@@ -80,7 +80,7 @@ class SQLConfSuite extends QueryTest with SharedSQLContext {
     val original = sqlContext.conf.numShufflePartitions
     try{
       sql(s"set ${SQLConf.Deprecated.MAPRED_REDUCE_TASKS}=10")
-      assert(ctx.conf.numShufflePartitions === 10)
+      assert(sqlContext.conf.numShufflePartitions === 10)
     } finally {
       sql(s"set ${SQLConf.SHUFFLE_PARTITIONS}=$original")
     }