fix(@angular/build): load zone.js dynamically for library unit tests #10633

Job	Run time
lint	2m 11s
build-e2e-windows	3m 38s
build	2m 50s
test	4m 34s
publish-snapshots	4m 34s
Browser Compatibility Tests	4m 35s
e2e-windows (24, esbuild, 5)	3m 45s
e2e-windows (24, esbuild, 3)	3m 46s
e2e-windows (24, esbuild, 0)	3m 46s
e2e-windows (24, esbuild, 1)	3m 46s
e2e-windows (24, esbuild, 4)	3m 47s
e2e-windows (24, webpack, 4)	3m 46s
e2e-windows (24, webpack, 2)	3m 47s
e2e-windows (24, esbuild, 2)	3m 46s
e2e-windows (24, webpack, 5)	3m 47s
e2e-windows (24, webpack, 0)	3m 45s
e2e-windows (24, webpack, 3)	3m 48s
e2e-windows (24, webpack, 1)	3m 49s
e2e-package-managers	1s
e2e	1s
e2e-snapshots	1s
	1h 7m 43s

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