fix(@schematics/angular): update default app component welcome message #2772

Job	Run time
list	25s
workflow (devkit-core-tests)	1m 16s
workflow (build-cli)	1m 50s
workflow (devkit-core-tests-rerun)	1m 33s
workflow (modules-builder-tests)	1m 49s
workflow (build-unit-tests)	2m 28s
	9m 21s

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