[dogfooding] Use String.join JDT cleanup in eclipse.debug The resulting code is much shorter. Change-Id: I2980ac23520edfbfa7648055cab8999ea69b1f6e Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com> Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.debug/+/179101 Tested-by: Platform Bot <platform-bot@eclipse.org> Reviewed-by: Alexander Kurtakov <akurtako@redhat.com>