Add support for validation jobs to `sync.ts`, and refactor #9323

Job	Run time
Split workflow (ubuntu-latest, linked)	1m 19s
Split workflow (ubuntu-latest, nightly-latest)	1m 28s
Split workflow (ubuntu-latest, default)	1m 16s
Split workflow (macos-latest, default)	2m 12s
Split workflow (macos-latest, nightly-latest)	1m 32s
Split workflow (macos-latest, linked)	1m 32s
	9m 19s

Provide feedback