refactor: remove version 20 migrations #1812

Job	Run time
lint	2m 15s
build	14s
e2e_windows (windows-2025, 22, npm, 1)	25s
e2e_windows (windows-2025, 22, npm, 4)	43s
e2e_windows (windows-2025, 22, npm, 2)	23s
e2e_windows (windows-2025, 22, npm, 3)	32s
e2e_windows (windows-2025, 22, npm, 0)	24s
e2e_windows (windows-2025, 22, esbuild, 2)	21s
e2e_windows (windows-2025, 22, esbuild, 1)	26s
e2e_windows (windows-2025, 22, esbuild, 4)	26s
e2e_windows (windows-2025, 22, esbuild, 3)	29s
e2e_windows (windows-2025, 22, esbuild, 5)	27s
e2e_windows (windows-2025, 22, esbuild, 0)	37s
e2e_windows (windows-2025, 22, npm, 5)	31s
test	0s
publish-snapshots	0s
Browser Compatibility Tests	0s
e2e-package-managers	0s
e2e	0s
e2e-snapshots	0s
	8m 13s

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