refactor(@schematics/angular): remove unneeded `getFileContent` unit-… #1810

Job	Run time
lint	2m 19s
build	22s
e2e_windows (windows-2025, 22, npm, 0)	31s
e2e_windows (windows-2025, 22, npm, 2)	31s
e2e_windows (windows-2025, 22, npm, 4)	27s
e2e_windows (windows-2025, 22, npm, 1)	36s
e2e_windows (windows-2025, 22, npm, 3)	29s
e2e_windows (windows-2025, 22, npm, 5)	27s
e2e_windows (windows-2025, 22, esbuild, 1)	29s
e2e_windows (windows-2025, 22, esbuild, 3)	26s
e2e_windows (windows-2025, 22, esbuild, 0)	22s
e2e_windows (windows-2025, 22, esbuild, 5)	22s
e2e_windows (windows-2025, 22, esbuild, 2)	31s
e2e_windows (windows-2025, 22, esbuild, 4)	26s
publish-snapshots	0s
test	0s
Browser Compatibility Tests	0s
e2e-snapshots	0s
e2e	0s
e2e-package-managers	0s
	8m 18s

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