tests: exclude learner endpoint from MemberPromote

[chaochn47]

Noticed a few test flakes of the newly added test. Usually etcd client will pick the first server address.

Fix is to exclude learner endpoint from MemberPromote.

2023-07-06T08:49:21.8398626Z     runtime_reconfiguration_test.go:181: 
2023-07-06T08:49:21.8400055Z         	Error Trace:	/home/runner/work/etcd/etcd/tests/e2e/runtime_reconfiguration_test.go:181
2023-07-06T08:49:21.8401843Z         	            				/home/runner/work/etcd/etcd/tests/e2e/runtime_reconfiguration_test.go:78
2023-07-06T08:49:21.8404818Z         	Error:      	Received unexpected error:
2023-07-06T08:49:21.8411142Z         	            	[/home/runner/work/etcd/etcd/bin/etcdctl --endpoints=http://localhost:20005 endpoint health] match not found.  Set EXPECT_DEBUG for more info Errs: [unexpected exit code [1] after running [/home/runner/work/etcd/etcd/bin/etcdctl --endpoints=http://localhost:20005 endpoint health]], last lines:
2023-07-06T08:49:21.8414992Z         	            	{"level":"warn","ts":"2023-07-06T08:49:21.826085Z","logger":"client","caller":"[email protected]/retry_interceptor.go:65","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc00036a000/localhost:20005","method":"/etcdserverpb.KV/Range","attempt":0,"error":"rpc error: code = FailedPrecondition desc = etcdserver: rpc not supported for learner"}
2023-07-06T08:49:21.8416546Z         	            	http://localhost:20005 is unhealthy: failed to commit proposal: etcdserver: rpc not supported for learner
2023-07-06T08:49:21.8417235Z         	            	Error: unhealthy cluster
2023-07-06T08:49:21.8418009Z         	            	 (expected "is healthy", got []). Try EXPECT_DEBUG=TRUE
2023-07-06T08:49:21.8418834Z         	Test:       	TestRuntimeReconfigGrowClusterSize/grow_cluster_size_from_1_to_3_with_learner

ref. https://github.com/etcd-io/etcd/actions/runs/5473356165/jobs/9966715425?pr=16189

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[wenjiaswe]

LGTM. Thanks!

Is #16193 failing this test because of the flakiness?

[ahrtr]

LGTM

Thanks @chaochn47

[chaochn47]

Is #16193 failing this test because of the flakiness?

I don't think so. This test has not yet backported to release-3.4 branch. I can look into the one you mentioned in the PR.

[wenjiaswe]

Is #16193 failing this test because of the flakiness?

I don't think so. This test has not yet backported to release-3.4 branch. I can look into the one you mentioned in the PR.

Ah ok, well, the other PR was failing on some kind of MemberPromote test but not failing any more. But thanks.