## Environment
**Liquibase Version**:
4.0.0 -> current (I'm testing on 4.2.2)

**Liquibase Integration & Version**: 
Java

**Liquibase Extension(s) & Version**: 
None

**Database Vendor & Version**:
ALL / not really relevant

**Operating System Type & Version**:
ALL / not really relevant

## Description
Regression of https://liquibase.jira.com/browse/CORE-3198, when merging 3.10 to 4.0 looks like this flag was accidentally wiped out.

## Steps To Reproduce
List the steps to reproduce the behavior.

1. Set property "liquibase.prefer.internal.xsd"
1. Disconnect internet, or open WireShark or similar tool
1. Run any XML changeset

## Actual Behavior
Running the changeset fails with

`Failed to read schema document 'http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.2.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>`

## Expected/Desired Behavior
It should use the XSD out of the jar

## Additional Context
Broken: ee233bd4c082f7e58de7ce5f7a2e6910a67f9f59

To fix add this code to the constructor of XMLChangeLogSAXParser (as in previous versions, eg: https://github.com/liquibase/liquibase/blob/a8b11044a571a11a7b904dfc7dce364fd0d49f37/liquibase-core/src/main/java/liquibase/parser/core/xml/XMLChangeLogSAXParser.java )
`
if (PREFER_INTERNAL_XSD) {
            InputStream xsdInputStream = XMLChangeLogSAXParser.class.getResourceAsStream(XSD_FILE);
            if (xsdInputStream != null) {
                try {
                    SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
                    Schema schema = schemaFactory.newSchema(new StreamSource(xsdInputStream));
                    saxParserFactory.setSchema(schema);
                    saxParserFactory.setValidating(false);
                } catch (SAXException e) {
                    LogService.getLog(XMLChangeLogSAXParser.class).warning("Could not load " + XSD_FILE + ", enabling parser validator", e);
                }
            }
        }
`


package liquibase.parser.core.xml;
import liquibase.Scope;
import liquibase.changelog.ChangeLogParameters;
import liquibase.exception.ChangeLogParseException;
import liquibase.parser.core.ParsedNode;
import liquibase.resource.ResourceAccessor;
import liquibase.util.BomAwareInputStream;
import liquibase.util.FileUtil;
import org.xml.sax.*;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.IOException;
import java.io.InputStream;
public class XMLChangeLogSAXParser extends AbstractChangeLogParser {
    public static final String LIQUIBASE_SCHEMA_VERSION = "4.1";
    private SAXParserFactory saxParserFactory;
    public XMLChangeLogSAXParser() {
        saxParserFactory = SAXParserFactory.newInstance();
        saxParserFactory.setValidating(true);
        saxParserFactory.setNamespaceAware(true);
    }
    @Override
    public int getPriority() {
        return PRIORITY_DEFAULT;
    }
    public static String getSchemaVersion() {
        return LIQUIBASE_SCHEMA_VERSION;
    }
    @Override
    public boolean supports(String changeLogFile, ResourceAccessor resourceAccessor) {