CDT cannot be built on Java 21 due to security manager changes

[Bananeweizen]

Describe the bug
On Java 21 the Maven build of CDT fails in every Maven module that needs to run Ant. I'm not sure if this failure is currently even relevant for the CDT project, since building on Java 17 continues to work fine. I'm fine with closing as "not relevant yet".

To Reproduce
Steps to reproduce the behavior:

cd cdt-root
set JAVA_HOME=your-jdk-21-location
mvn verify

Screenshots

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:3.1.0:run (generate-configuration) on project org.eclipse.cdt.debug.application: An Ant BuildException has occured: The following error occurred while executing this line:
[ERROR] C:\dev\cdt-main\git\cdt\debug\org.eclipse.cdt.debug.application\configGenerator.xml:4: java.lang.UnsupportedOperationException: The Security Manager is deprecated and will be removed in a future release
[ERROR] around Ant part ...<ant antfile="configGenerator.xml" target="generate.configuration" />... @ 6:74 in C:\dev\cdt-main\git\cdt\debug\org.eclipse.cdt.debug.application\target\antrun\build-main.xml

Version Information (please complete the following information):
HEAD

Additional context
There was a discussion somewhere in platform about Ant being problematic on Java 21, because the exception handling of the Ant plugin in Eclipse relies on the security manager to capture the "exit" of the embedded Ant. That's probably exactly the same issue.