fix(@angular/build): revert setup unit-test polyfills before TestBed … #1566

Job	Run time
lint	2m 7s
build	10s
e2e_windows (windows-2025, 22, npm, 1)	29s
e2e_windows (windows-2025, 22, npm, 0)	37s
e2e_windows (windows-2025, 22, npm, 4)	30s
e2e_windows (windows-2025, 22, npm, 3)	27s
e2e_windows (windows-2025, 22, npm, 2)	1m 24s
e2e_windows (windows-2025, 22, esbuild, 0)	1m 15s
e2e_windows (windows-2025, 22, esbuild, 3)	38s
e2e_windows (windows-2025, 22, esbuild, 1)	37s
e2e_windows (windows-2025, 22, esbuild, 5)	39s
e2e_windows (windows-2025, 22, esbuild, 4)	38s
e2e_windows (windows-2025, 22, esbuild, 2)	38s
e2e_windows (windows-2025, 22, npm, 5)	1m 43s
Browser Compatibility Tests	0s
publish-snapshots	0s
test	0s
e2e	0s
e2e-snapshots	0s
e2e-package-managers	0s
	11m 52s

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