You should find them in a file :
${JENKINS_HOME}/org.jenkinsci.plugins.configfiles.GlobalConfigFiles.xml
The format is xml, based on content.
There's the "managed-scripts" plugin section.
eg:
<?xml version='1.1' encoding='UTF-8'?>
<org.jenkinsci.plugins.configfiles.GlobalConfigFiles plugin="[email protected]">
<configs class="sorted-set">
<comparator class="org.jenkinsci.plugins.configfiles.GlobalConfigFiles$1"/>
<org.jenkinsci.plugins.configfiles.groovy.GroovyScript>
</org.jenkinsci.plugins.configfiles.groovy.GroovyScript>
<org.jenkinsci.plugins.configfiles.maven.GlobalMavenSettingsConfig>
</org.jenkinsci.plugins.configfiles.maven.GlobalMavenSettingsConfig>
<org.jenkinsci.plugins.configfiles.maven.MavenSettingsConfig>
</org.jenkinsci.plugins.configfiles.maven.MavenSettingsConfig>
<org.jenkinsci.plugins.managedscripts.ScriptConfig plugin="[email protected]">
</org.jenkinsci.plugins.managedscripts.ScriptConfig>
</configs>
</org.jenkinsci.plugins.configfiles.GlobalConfigFiles>
addendum: To answer the more general, implied portion of the question, suggest you review: Administering Jenkins.
+- config.xml (jenkins root configuration)
+- *.xml (other site-wide configuration files)
+- plugins/ (stores plugins)
Progressively, many configurations which used to reside in the config.xml have been split into specific files per plugin (as plugins are updated). Not sure where that was specified.
You probably will find you need all of ${JENKINS_HOME}/*.xml to be copied to your new server, along with the plugins in ${JENKINS_HOME}/plugins/*