Use maven batch mode in k8s-operator CI

Currently, the GitHub workflows do not use batch mode in the k8s-operator repo, so there are a lot of lines in the log like this:

Progress (1): 4.1/14 kB
Progress (1): 8.2/14 kB
Progress (1): 12/14 kB 
Progress (1): 14 kB

To produce logs that are for more easy to navigate, all mvn calls should apply the batch-mode option -B.