`jetty-servlet-api-4.0.6.jar` is missing jsp xsd references

When running with validate on in Jetty 12.x `ee8` environment, it is not possible to use the XSD's in the `jetty-servlet-api-4.0.6.jar` to validate the descriptors.

Take the following log for example.

* Running org.eclipse.jetty.ee8.webapp.WebAppContextTest.testCustomXmlParser(WorkDir)
2026-01-13 15:07:18.573:WARN :oejx.XmlParser:ForkJoinPool-1-worker-1: SAX Parse Issue @jar:file:///home/jenkins/agent/workspace/jetty.project_PR-14210/.repository/org/eclipse/jetty/toolchain/jetty-servlet-api/4.0.6/jetty-servlet-api-4.0.6.jar!/javax/servlet/resources/web-common_3_1.xsd line:104 col:46 : org.xml.sax.SAXParseException; systemId: jar:file:///home/jenkins/agent/workspace/jetty.project_PR-14210/.repository/org/eclipse/jetty/toolchain/jetty-servlet-api/4.0.6/jetty-servlet-api-4.0.6.jar!/javax/servlet/resources/web-common_3_1.xsd; lineNumber: 104; columnNumber: 46; schema_reference.4: Failed to read schema document 'jsp_2_3.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not .
* 2026-01-13 15:07:18.615:ERROR:oejx.XmlParser:ForkJoinPool-1-worker-1: SAX Parse Issue @jar:file:///home/jenkins/agent/workspace/jetty.project_PR-14210/.repository/org/eclipse/jetty/toolchain/jetty-servlet-api/4.0.6/jetty-servlet-api-4.0.6.jar!/javax/servlet/resources/web-common_3_1.xsd line:142 col:50 : org.xml.sax.SAXParseException; systemId: jar:file:///home/jenkins/agent/workspace/jetty.project_PR-14210/.repository/org/eclipse/jetty/toolchain/jetty-servlet-api/4.0.6/jetty-servlet-api-4.0.6.jar!/javax/servlet/resources/web-common_3_1.xsd; lineNumber: 142; columnNumber: 50; src-resolve: Cannot resolve the name 'javaee:jsp-configType' to a(n) 'type definition' component.
* 2026-01-13 15:07:18.616:ERROR:oejx.XmlParser:ForkJoinPool-1-worker-1: SAX Parse Issue @jar:file:///home/jenkins/agent/workspace/jetty.project_PR-14210/.repository/org/eclipse/jetty/toolchain/jetty-servlet-api/4.0.6/jetty-servlet-api-4.0.6.jar!/javax/servlet/resources/web-common_3_1.xsd line:745 col:50 : org.xml.sax.SAXParseException; systemId: jar:file:///home/jenkins/agent/workspace/jetty.project_PR-14210/.repository/org/eclipse/jetty/toolchain/jetty-servlet-api/4.0.6/jetty-servlet-api-4.0.6.jar!/javax/servlet/resources/web-common_3_1.xsd; lineNumber: 745; columnNumber: 50; src-resolve: Cannot resolve the name 'javaee:jsp-fileType' to a(n) 'type definition' component.
* 2026-01-13 15:07:18.632:WARN :oeje8w.Descriptor:ForkJoinPool-1-worker-1: Unable to parse file:/home/jenkins/agent/workspace/jetty.project_PR-14210/jetty-ee8/jetty-ee8-webapp/target/classes/org/eclipse/jetty/ee8/webapp/webdefault-ee8.xml
org.xml.sax.SAXParseException; systemId: jar:file:///home/jenkins/agent/workspace/jetty.project_PR-14210/.repository/org/eclipse/jetty/toolchain/jetty-servlet-api/4.0.6/jetty-servlet-api-4.0.6.jar!/javax/servlet/resources/web-common_3_1.xsd; lineNumber: 142; columnNumber: 50; src-resolve: Cannot resolve the name 'javaee:jsp-configType' to a(n) 'type definition' component.

The above log shows that `javax/servlet/resources/web-common_3_1.xsd` references a XSD name like `javaee:jsp-configType`.
But that definition would be in the `javax/servlet/resources/jsp-*.xsd` files, which are not present in the `jetty-servlet-api-4.0.6.jar` file.