refactor(@schematics/angular): remove migrations that cannot be used … #1688

Job	Run time
list	23s
workflow (devkit-core-tests-rerun)	24s
workflow (build-cli)	26s
workflow (build-unit-tests)	24s
workflow (devkit-core-tests)	25s
workflow (modules-builder-tests)	24s
	2m 26s

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