Delete obsolete test utility method

Commit dc6ce30663 made this method obsolete.

spring-expression/src/test/java/org/springframework/expression/spel/SetValueTests.java

@@ -268,18 +268,6 @@ class SetValueTests extends AbstractExpressionTests {
 		return parser.parseExpression(expressionString);
 	}
 
-	/**
-	 * Call setValue() but expect it to fail.
-	 */
-	private void setValueAndExpectError(String expression, Object value) {
-		Expression e = parser.parseExpression(expression);
-		assertThat(e).isNotNull();
-		if (DEBUG) {
-			SpelUtilities.printAbstractSyntaxTree(System.out, e);
-		}
-		assertThatSpelEvaluationException().isThrownBy(() -> e.setValue(context, value));
-	}
-
 	/**
 	 * Call setValue() but expect it to fail.
 	 * @see #evaluateAndCheckError(org.springframework.expression.ExpressionParser, String, Class, SpelMessage, Object...)