refactor(@angular/cli): use command default for unspecified target bu… #8971

Job	Run time
build	1m 41s
lint	1m 41s
build-e2e-windows	1m 42s
test	1s
Browser Compatibility Tests	1s
e2e	1s
publish-snapshots	1s
e2e-package-managers	1s
e2e-snapshots	1s
e2e-windows	1s
	5m 11s

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