release: cut the v21.2.0-rc.1 release #3053

Job	Run time
list	24s
workflow (build-cli)	1m 55s
workflow (devkit-core-tests)	1m 30s
workflow (devkit-core-tests-rerun)	1m 34s
workflow (build-unit-tests)	2m 33s
workflow (modules-builder-tests)	1m 53s
	9m 49s

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