Use workspace JRE version to run Eclipse external builder (Ant builder)

[bahnwaerter]

The external builder of Eclipse RCP 2023-06 in combination with Ant 1.10.x requires for the execution of the builder a JRE version >= 11. Therefore, the JRE version of all external Ant builders is bumped to the workspace default (JRE from JDK version >= 11).

[bahnwaerter]

@danieldietsch and @schuessf, you are welcome to test this out in a fresh workspace with the latest Eclipse RCP version. Hopefully this will work on Windows too, but I haven't checked it there yet.

[schuessf]

For me everything is working, but I also did not have any issues before 😉

[danieldietsch]

Looks good!