Refactor load balancer server list and health checking #431

Job	Run time
build / Build	7m 8s
E2E Tests (startup)	10m 30s
Docker Tests (basics)	1m 9s
E2E Tests (s3)	9m 25s
Docker Tests (bootstraptoken)	43s
E2E Tests (btrfs)	3m 54s
Docker Tests (cacerts)	49s
E2E Tests (externalip)	6m 5s
Docker Tests (compat)	2m 37s
E2E Tests (privateregistry)	7m 7s
Docker Tests (lazypull)	49s
E2E Tests (embeddedmirror)	5m 47s
Docker Tests (upgrade)	2m 19s
E2E Tests (wasm)	4m 33s
	1h 2m 55s

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