Remove tests from Ant repository for launch migration. The option to
migrate a very old workspace has been removed in 4.17 so this code is
not useful anymore, see
https://www.eclipse.org/eclipse/news/4.17/platform.php#workspace-migration

Change-Id: Iebeadc7c32a1eadc64ecb716f7c69bfb44844c1c
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform/+/183931
Tested-by: Platform Bot <platform-bot@eclipse.org>