remove tests for removed methods

Author: brkyvz

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala

@@ -1253,18 +1253,6 @@ class ExpressionEvaluationSuite extends ExpressionEvaluationBaseSuite {
     unaryMathFunctionEvaluation[Double](Signum, math.signum)
   }
 
-  test("isignum") {
-    unaryMathFunctionEvaluation[Int](ISignum, math.signum, (-5 to 5))
-  }
-
-  test("fsignum") {
-    unaryMathFunctionEvaluation[Float](FSignum, math.signum, (-5 to 5).map(_.toFloat))
-  }
-
-  test("lsignum") {
-    unaryMathFunctionEvaluation[Long](LSignum, math.signum, (5 to 5).map(_.toLong))
-  }
-
   test("log") {
     unaryMathFunctionEvaluation(Log, math.log, (0 to 20).map(_ * 0.1))
     unaryMathFunctionEvaluation(Log, math.log, (-5 to -1).map(_ * 0.1), true)

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

@@ -194,18 +194,6 @@ class MathExpressionsSuite extends QueryTest {
     testOneToOneMathFunction[Double](signum, math.signum)
   }
 
-  test("isignum") {
-    testOneToOneMathFunction[Int](isignum, math.signum)
-  }
-
-  test("fsignum") {
-    testOneToOneMathFunction[Float](fsignum, math.signum)
-  }
-
-  test("lsignum") {
-    testOneToOneMathFunction[Long](lsignum, math.signum)
-  }
-
   test("pow") {
     testTwoToOneMathFunction(pow, pow, math.pow)
   }