Bug 577522 - Remove unused older easymock, include multiple mockito

Older easymock version isn't used anymore, so we remove it.
While transitioning to upstream mockito, include the upstream bundle as
well as the Orbit clone.

Change-Id: I13134318669c8b5e857a7037579a663f60d665bf
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.releng/+/188411
Tested-by: Mickael Istria <mistria@redhat.com>
Reviewed-by: Mickael Istria <mistria@redhat.com>