Bug 573960 - POM and product version change for 4.21 release

Change-Id: Icbeab9556782cf1441ed978b5108e1d9e52656d8
Signed-off-by: Sravan Kumar Lakkimsetti <sravankumarl@in.ibm.com>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.team/+/181371
28 files changed