Bump version to "v21.0.0-next.9" with changelog. #9361

Job	Run time
analyze	4s
lint	2m 32s
build-e2e-windows-subset	6m 2s
build	5m 51s
e2e-package-managers (ubuntu-latest, 22, yarn, 0)	8m 18s
test	3m 33s
e2e-package-managers (ubuntu-latest, 22, pnpm, 0)	6m 23s
e2e-package-managers (ubuntu-latest, 22, pnpm, 2)	5m 32s
e2e-package-managers (ubuntu-latest, 22, yarn, 1)	6m 21s
e2e-package-managers (ubuntu-latest, 22, pnpm, 1)	5m 7s
e2e-package-managers (ubuntu-latest, 22, yarn, 2)	7m 18s
e2e (ubuntu-latest, 22, npm, 2)	10m 40s
e2e (ubuntu-latest, 22, npm, 0)	11m 36s
e2e (ubuntu-latest, 22, npm, 1)	12m 18s
e2e (ubuntu-latest, 22, npm, 4)	9m 19s
e2e (ubuntu-latest, 22, esbuild, 0)	8m 39s
e2e (ubuntu-latest, 22, npm, 3)	8m 50s
e2e (ubuntu-latest, 22, esbuild, 4)	6m 15s
e2e (ubuntu-latest, 22, npm, 5)	9m 57s
e2e-snapshots	0s
e2e (ubuntu-latest, 22, esbuild, 3)	8m 40s
e2e (ubuntu-latest, 22, esbuild, 2)	8m 16s
e2e (ubuntu-latest, 22, esbuild, 5)	6m 55s
e2e (ubuntu-latest, 22, esbuild, 1)	9m 29s
e2e-windows-subset	4m 2s
	2h 51m 57s

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