e2e: add cluster version test with rolling start servers

[YoyinZyc]

In #11282, we added a test for cluster version check. However, the cluster in test environment will start servers at the same time so that this test will not cover cluster version compatibility check.
In this pr, the added test will start servers one by one and then verify the cluster version.
@wenjiaswe @jingyih Please have a look.

[codecov-io]

Codecov Report

Merging #11287 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11287      +/-   ##
==========================================
- Coverage   64.65%   64.65%   -0.01%     
==========================================
  Files         403      403              
  Lines       37956    37956              
==========================================
- Hits        24542    24541       -1     
- Misses      11777    11783       +6     
+ Partials     1637     1632       -5

Impacted Files	Coverage Δ
client/client.go	65.03% <0%> (-18.96%)	⬇️
etcdserver/api/v3rpc/lease.go	69.31% <0%> (-5.69%)	⬇️
proxy/grpcproxy/watcher.go	89.79% <0%> (-4.09%)	⬇️
pkg/testutil/recorder.go	77.77% <0%> (-3.71%)	⬇️
clientv3/op.go	72.5% <0%> (-1.25%)	⬇️
clientv3/balancer/resolver/endpoint/endpoint.go	81.73% <0%> (-0.87%)	⬇️
etcdserver/server.go	68.59% <0%> (+0.33%)	⬆️
clientv3/watch.go	92% <0%> (+0.42%)	⬆️
clientv3/leasing/cache.go	87.77% <0%> (+0.55%)	⬆️
clientv3/leasing/kv.go	90.36% <0%> (+0.66%)	⬆️
... and 17 more

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[jingyih]

For context, this is needed in order to exercise the following code path where in a 3-node cluster, 2 nodes are up and therefore has a leader but the cluster version is undecided because the info of the 3rd node is unknown.

etcd/etcdserver/server.go

Lines 2463 to 2467 in b5afbdd

	if s.Leader() != s.ID() {
	continue
	}
	v := decideClusterVersion(s.getLogger(), getVersions(s.getLogger(), s.cluster, s.id, s.peerRt))

[jingyih]

LGTM

[jingyih]

Ideally we should avoid using Sleep() for timing, but I do not have a better idea.