Add a `reapAllVats` method to the controller #28080

Job	Run time
pre_check / Check preconditions and cancel previous jobs	4s
deployment-test	29m 53s
set-integration-result-in-progress	5s
test-docker-build	7m 46s
getting-started (link-cli/yarn)	9m 20s
getting-started (registry/yarn)	14m 54s
getting-started (registry/npm)	14m 59s
getting-started (registry/npx)	14m 38s
finalize-integration-result	6s
	1h 31m 45s

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