fix(@schematics/angular): remove constructor from service template #1400

Job	Run time
list	24s
workflow (build-cli)	1m 25s
workflow (modules-builder-tests)	1m 36s
workflow (devkit-core-tests-rerun)	1m 14s
workflow (build-unit-tests)	2m 3s
workflow (devkit-core-tests)	1m 7s
	7m 49s

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