use latest version of maven in the jenkinsfile

[dvojtise]

Due to the recent maven version increase from 3.8.6 to 3.9.0 ( message https://www.eclipse.org/lists/cross-project-issues-dev 06/04/2023)
our build was failing

I temporarily disabled apache-maven-latest and use apache-maven-3.8.6 in our jenkinsfile
(cf. 1ff4816 )

We need to switch back to latest when a compatible version will be available again

cf. https://wiki.eclipse.org/Jenkins#Apache_Maven