Remove JAXB dependency from performance plugin

Starting with Java 9+, JAXB has been removed from the JDK. So it's a good thing to try and break/remove the dependency against from plugins who do not really use JAXB for its core feature (object de/serialization).

https://github.com/jenkinsci/performance-plugin/search?q=javax.xml.bind&unscoped_q=javax.xml.bind shows the usage of JAXB.

Acceptance criteria:

• https://github.com/jenkinsci/performance-plugin/search?q=javax.xml.bind&unscoped_q=javax.xml.bind should yield nothing