Rework StringUtilsTest from plain JUnit to ESTestCase

Original commit: elastic/x-pack-elasticsearch@cd16043f23

sql/server/src/test/java/org/elasticsearch/xpack/sql/util/StringUtilsTests.java

@@ -5,49 +5,40 @@
  */
 package org.elasticsearch.xpack.sql.util;
 
-import org.junit.Test;
+import org.elasticsearch.test.ESTestCase;
 
 import static org.elasticsearch.xpack.sql.util.StringUtils.sqlToJavaPattern;
-import static org.junit.Assert.assertEquals;
 
-public class StringUtilsTest {
+public class StringUtilsTests extends ESTestCase {
 
-    @Test
     public void testNoRegex() {
         assertEquals("^fooBar$", sqlToJavaPattern("fooBar"));
     }
 
-    @Test
     public void testEscapedJavaRegex() {
         assertEquals("^\\.\\d$", sqlToJavaPattern("\\.\\d"));
     }
 
-    @Test
     public void testSimpleSqlRegex1() {
         assertEquals("^foo.bar$", sqlToJavaPattern("foo_bar"));
     }
 
-    @Test
     public void testSimpleSqlRegex2() {
         assertEquals("^foo.*bar$", sqlToJavaPattern("foo%bar"));
     }
 
-    @Test
     public void testMultipleSqlRegexes() {
         assertEquals("^foo.*bar.$", sqlToJavaPattern("foo%bar_"));
     }
 
-    @Test
     public void testJavaRegexNoSqlRegex() {
         assertEquals("^foo\\.\\*bar$", sqlToJavaPattern("foo.*bar"));
     }
 
-    @Test
     public void testMultipleRegexAndSqlRegex() {
         assertEquals("^foo\\.\\*bar\\..*$", sqlToJavaPattern("foo.*bar.%"));
     }
 
-    @Test
     public void testComplicatedJavaRegex() {
         assertEquals("^\\^\\[\\d\\]\\.\\*\\$$", sqlToJavaPattern("^[\\d].*$"));
     }