Improve customization of training_setup.sh script

This is a quick fix PR addressing the comments in https://github.com/openmicroscopy/openmicroscopy/pull/2594#discussion_r13640525.

To test this PR, check the merge-integration/merge-training job still run as expected.
In these lines I don't think the first pair of quotes achieves anything, but they are harmless. (We don't need to quote anything actually inside the `ice.config` file, right?)