refactor(@angular/build): clean up duplicate of code in the karma bui… #1701

Job	Run time
build	18s
lint	2m 28s
e2e_windows (windows-2025, 22, npm, 0)	39s
e2e_windows (windows-2025, 22, npm, 1)	48s
e2e_windows (windows-2025, 22, esbuild, 0)	54s
e2e_windows (windows-2025, 22, npm, 5)	54s
e2e_windows (windows-2025, 22, npm, 2)	33s
e2e_windows (windows-2025, 22, npm, 4)	59s
e2e_windows (windows-2025, 22, esbuild, 1)	55s
e2e_windows (windows-2025, 22, esbuild, 5)	38s
e2e_windows (windows-2025, 22, esbuild, 2)	29s
e2e_windows (windows-2025, 22, esbuild, 3)	1m 4s
e2e_windows (windows-2025, 22, esbuild, 4)	36s
e2e_windows (windows-2025, 22, npm, 3)	48s
Browser Compatibility Tests	0s
test	0s
publish-snapshots	0s
e2e	0s
e2e-package-managers	0s
e2e-snapshots	0s
	12m 3s

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