WFLY-3443 JCA tracking should default to false for datasources

What was the behavior of the legacy servers? My guess is 'false'. This should discard whatever was the equivalent to the legacy behavior and then reject anything defined. So if the legacy behavior was 'false':

```
.setDiscard(new DiscardAttributeChecker.DefaultDiscardAttributeChecker() {
                    @Override
                    protected boolean isValueDiscardable(PathAddress address, String attributeName, ModelNode attributeValue, TransformationContext context) {
                        return attributeValue.equals(new ModelNode(false));
                    }
                }, TRACKING)
                .addRejectCheck(RejectAttributeChecker.DEFINED, TRACKING)
```

If the legacy behavior was 'true', then

```
.setDiscard(new DiscardAttributeChecker.DefaultDiscardAttributeChecker(false, false) {
                    @Override
                    protected boolean isValueDiscardable(PathAddress address, String attributeName, ModelNode attributeValue, TransformationContext context) {
                        return attributeValue.equals(new ModelNode(true));
                    }
                }, TRACKING)
                .addRejectCheck(RejectAttributeChecker.DEFINED, TRACKING)
```

(Note the different DefaultDiscardAttributeChecker constructor call in the 'true' case.)

Hmm, in the 'true' case, the reject check needs to reject both DEFINED and UNDEFINED. A manual RejectAttributeChecker can be written for that, but I'll add one to wildfly-core now.