testing/jdtls: upgrade to 1.24.0
https://github.com/eclipse/eclipse.jdt.ls/blob/v1.24.0/CHANGELOG.md
takes ages to build, but at least seems to be working
https://github.com/eclipse/eclipse.jdt.ls/blob/v1.24.0/CHANGELOG.md
takes ages to build, but at least seems to be working