Adjust configuration to run tests with tycho

* Remove workaround adding org.eclipse.equinox.event as it's no longer
needed.
* Adjust extra target-platform items to have JDT JUnit runtimes so all
deps are there.

Change-Id: Iddc44c7eb81ce1a42fa90d8dc79aa515464d38cc
Reviewed-on: https://git.eclipse.org/r/c/equinox/rt.equinox.framework/+/191640
Tested-by: Equinox Bot <equinox-bot@eclipse.org>
Reviewed-by: Alexander Kurtakov <akurtako@redhat.com>