Remove WelcomeBannerRegistry in favor of reactive solution

Co-authored-by: Mikko Aspiala <mikko.aspiala@gmail.com>
Signed-off-by: Janne Savolainen <janne.savolainen@live.fi>

src/extensions/extension-loader/extension-loader.ts

@@ -263,7 +263,6 @@ export class ExtensionLoader {
         registries.EntitySettingRegistry.getInstance().add(extension.entitySettings),
         registries.StatusBarRegistry.getInstance().add(extension.statusBarItems),
         registries.CommandRegistry.getInstance().add(extension.commands),
-        registries.WelcomeBannerRegistry.getInstance().add(extension.welcomeBanners),
         registries.CatalogEntityDetailRegistry.getInstance().add(extension.catalogEntityDetailItems),
         registries.TopBarRegistry.getInstance().add(extension.topBarItems),
       ];