refactor(@schematics/angular): remove v19 migrations #7417

Job	Run time
build	35s
lint	35s
e2e_windows (windows-2025, 22, npm, 0)	21s
e2e_windows (windows-2025, 22, npm, 1)	21s
e2e_windows (windows-2025, 22, npm, 2)	21s
e2e_windows (windows-2025, 22, npm, 3)	20s
e2e_windows (windows-2025, 22, npm, 4)	20s
e2e_windows (windows-2025, 22, npm, 5)	20s
e2e_windows (windows-2025, 22, esbuild, 0)	19s
e2e_windows (windows-2025, 22, esbuild, 1)	26s
e2e_windows (windows-2025, 22, esbuild, 2)	18s
e2e_windows (windows-2025, 22, esbuild, 3)	20s
e2e_windows (windows-2025, 22, esbuild, 4)	18s
e2e_windows (windows-2025, 22, esbuild, 5)	12s
publish-snapshots	1s
Browser Compatibility Tests	1s
test	1s
e2e	1s
e2e-snapshots	1s
e2e-package-managers	1s
	5m 12s

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