Add missing redirect to `/dev/null` for `downloadIfNotExist` in `refreshServerJar`.

Signed-off-by: Arthur McLain <mclain.it@gmail.com>

chore: Add borderless-(neo)forge, improvedsignediting, guicompass, mmogscheatsmenu, hidehands, lunarblockoverlay - Thanks to @Tralty @ModernGamingWorld for the reports!

Closes https://github.com/Griefed/ServerPackCreator/issues/797 Closes https://github.com/Griefed/ServerPackCreator/issues/755 Closes https://github.com/Griefed/ServerPackCreator/issues/752 Closes https://github.com/Griefed/ServerPackCreator/issues/744 Closes https://github.com/Griefed/ServerPackCreator/issues/754 Closes https://github.com/Griefed/ServerPackCreator/issues/776

fix: add missing redirect to `/dev/null` in default_template.sh

fix: update default_template.sh

See merge request !647