[JENKINS-42724] - Restore the windows-service/jenkins.xml resource to restore...

[JENKINS-42724] - Restore the windows-service/jenkins.xml resource to restore compatibility with windows-slaves 1.2 (#2803)

* [JENKINS-42724] - Restore the jenkins-slave.xml file

Windows Slaves plugin performs a direct access to the resources bundled into the core.
Hence the file removal was a bad idea though I have not seen the issue in automatic tests and ATH.

This change also was a last-minute change in https://github.com/jenkinsci/jenkins/pull/2765/ in order to address suggestions from @daniel-beck, hence I didn't test it properly

* [JENKINS-42724] - Update the Windows Agents plugin dependency to 1.3.1

* [JENKINS-42724]  -Revert the war/pom.xml upgrade