The documentation mentions various NativeJdbcExtractors that no longer
exist. To be specific CommonsDbcpNativeJdbcExtractor and
XAPoolNativeJdbcExtractor no longer exist.
This commit includes the following changes:
* remove CommonsDbcpNativeJdbcExtractor references from Asciidoctor
* remove CommonsDbcpNativeJdbcExtractor references from Javadoc
* remove XAPoolNativeJdbcExtractor references from Asciidoctor
Issue: SPR-14810
Closes gh-1205