refactor(@angular/build): default tsConfig option in unit-test builder #2063

Job	Run time
lint	2m 16s
build	26s
build-e2e-windows	34s
e2e	0s
test	0s
Browser Compatibility Tests	-1s
e2e-package-managers	-1s
publish-snapshots	-1s
e2e-snapshots	-1s
e2e-windows	0s
	3m 12s

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