[Sirius][Diagram] Remove the contribution to org.eclipse.ui.startup for Sirius Diagram

Bugzilla Link	579709
Status	NEW
Importance	P3 normal
Reported	Apr 15, 2022 04:51 EDT
Modified	Apr 15, 2022 08:16 EDT
Version	0.7.0
See also	Gerrit change 192767, Git commit 033be04e

Description

The plugins org.eclipse.papyrus.uml.sirius.clazz.diagram, org.eclipse.papyrus.uml.sirius.sequence.diagram, org.eclipse.papyrus.uml.sirius.statemachine.diagram contributes to org.eclipse.ui.startup. This contribution is useless and can be removed.