releng: Remove RCP features from non-RCP update site

releng: Remove RCP features from non-RCP update site

The RCP version has its own update site now. This should avoid
the problems of Eclipse plugin users installing the RCP features
by mistake.

Manually added the RCP source features in the RCP update site.

Change-Id: I7e001397cf2d6a65fc8687d89ebb811d290a0694
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/41466
Reviewed-by: Hudson CI
Reviewed-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Tested-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>