fix(@angular/build): setup unit-test polyfills before TestBed init #1562

Job	Run time
build	12s
lint	2m 9s
e2e_windows (windows-2025, 22, npm, 1)	28s
e2e_windows (windows-2025, 22, npm, 2)	45s
e2e_windows (windows-2025, 22, npm, 0)	30s
e2e_windows (windows-2025, 22, esbuild, 0)	45s
e2e_windows (windows-2025, 22, esbuild, 1)	40s
e2e_windows (windows-2025, 22, npm, 3)	38s
e2e_windows (windows-2025, 22, esbuild, 3)	44s
e2e_windows (windows-2025, 22, npm, 4)	41s
e2e_windows (windows-2025, 22, esbuild, 2)	29s
e2e_windows (windows-2025, 22, esbuild, 4)	1m 23s
e2e_windows (windows-2025, 22, npm, 5)	28s
e2e_windows (windows-2025, 22, esbuild, 5)	29s
Browser Compatibility Tests	-1s
e2e-package-managers	0s
e2e	0s
e2e-snapshots	0s
test	0s
publish-snapshots	-1s
	10m 19s

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