refactor(@schematics/angular): remove migrations that cannot be used … #2758

Job	Run time
build	21s
build-e2e-windows	27s
lint	1m 54s
publish-snapshots	0s
Browser Compatibility Tests	0s
test	0s
e2e-package-managers	0s
e2e	0s
e2e-snapshots	0s
e2e-windows	0s
	2m 42s

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