remove unused

Author: KevinGe00

coral-spark/src/test/java/com/linkedin/coral/spark/CoralSparkTest.java

@@ -265,7 +265,6 @@ public void testLateralViewOuter() {
   public void testLateralViewOuterWithExtractUnion() {
     RelNode relNode = TestUtils.toRelNode(String.join("\n", "", "SELECT extract_union(ut), t.ccol", "FROM complex",
         "LATERAL VIEW OUTER explode(complex.c) t as ccol"));
-    String relNodePlan = RelOptUtil.toString(relNode);
     String convertToSparkSql = createCoralSpark(relNode).getSparkSql();
 
     String targetSql = "SELECT coalesce_struct(complex.ut, 'uniontype<int>'), t0.ccol\n"