HSEARCH-2172 Fix ElasticsearchNullValueIT.testProjectionOfNullValues

There was an issue in GolfPlayer.Builder that altered the value of
GolfPlayer.active when it wasn't explicitly initialized.

The issue didn't show up before because the value was being initialized
with "false", which was indexed as null because of the bug we just
fixed.

elasticsearch/src/test/java/org/hibernate/search/elasticsearch/test/GolfPlayer.java

@@ -212,7 +212,7 @@ public static class Builder {
 
 		private String firstName;
 		private String lastName;
-		private boolean active;
+		private Boolean active;
 		private Date dateOfBirth;
 		private Calendar subscriptionEndDate;
 		private double handicap;