Fix put mapping request validators random test

This commit fixes a test bug in the request validators random test. In
particular, an assertion was not properly nested in a guard that would
ensure that was at least one failure.

Relates #43000

Author: jasontedor

server/src/test/java/org/elasticsearch/action/admin/indices/mapping/put/TransportPutMappingRequestValidatorsTests.java

@@ -84,8 +84,8 @@ public void testRandom() {
             assertNull(e);
         } else {
             assertNotNull(e);
+            assertThat(e.getSuppressed(), Matchers.arrayWithSize(numberOfFailures - 1));
         }
-        assertThat(e.getSuppressed(), Matchers.arrayWithSize(numberOfFailures - 1));
     }
 
 }