DEFAULT FIELD - fix anonymizer tests

Signed-off-by: Jialiang Liang <jiallian@amazon.com>

Author: RyanL1997

ppl/src/test/java/org/opensearch/sql/ppl/utils/PPLQueryDataAnonymizerTest.java

@@ -515,7 +515,6 @@ public void testPatterns() {
   public void testRegex() {
     assertEquals("source=t | regex field=***", anonymize("source=t | regex field='pattern'"));
     assertEquals("source=t | regex field!=***", anonymize("source=t | regex field!='pattern'"));
-    assertEquals("source=t | regex ***", anonymize("source=t | regex 'pattern'"));
     assertEquals(
         "source=t | regex email=*** | fields + email",
         anonymize("source=t | regex email='.*@domain.com' | fields email"));