server: v2store deprecation: Prepare to use publishV3 instead of publish V2.

[ptabor]

Part of: #12800

Had to fix:

• etcdctl backup command such that it scrubs additionally 'cluster_member_attr_set' commands from the WAL log (apart of other membership-driven-commands):

Without the fix, the process used to fail with:

./build.sh && (cd tests && EXPECT_DEBUG=true 'env' 'go' 'test' '-timeout=30m' '--count=1' 'go.etcd.io/etcd/tests/v3/e2e' --run TestCtlV2BackupV3$ -v)

{"level":"panic","ts":"2021-03-26T11:11:08.794+0100","caller":"membership/cluster.go:445","msg":"failed to update; member unknown","cluster-id":"786e04252702","local-member-id":"786e04252701","unknown-remote-peer-id":"ca50e9357181d758","stacktrace":"go.etcd.io/etcd/server/v3/etcdserver/api/membership.(*RaftCluster).UpdateAttributes\n\t/home/ptab/corp/etcd/server/etcdserver/api/membership/cluster.go:445\ngo.etcd.io/etcd/server/v3/etcdserver.(*applierV3backend).ClusterMemberAttrSet\n\t/home/ptab/corp/etcd/server/etcdserver/apply.go:911\ngo.etcd.io/etcd/server/v3/etcdserver.(*applierV3backend).Apply\n\t/home/ptab/corp/etcd/server/etcdserver/apply.go:229\ngo.etcd.io/etcd/server/v3/etcdserver.(*authApplierV3).Apply\n\t/home/ptab/corp/etcd/server/etcdserver/apply_auth.go:60\ngo.etcd.io/etcd/server/v3/etcdserver.(*EtcdServer).applyEntryNormal\n\t/home/ptab/corp/etcd/server/etcdserver/server.go:2111\ngo.etcd.io/etcd/server/v3/etcdserver.(*EtcdServer).apply\n\t/home/ptab/corp/etcd/server/etcdserver/server.go:2024\ngo.etcd.io/etcd/server/v3/etcdserver.(*EtcdServer).applyEntries\n\t/home/ptab/corp/etcd/server/etcdserver/server.go:1279\ngo.etcd.io/etcd/server/v3/etcdserver.(*EtcdServer).applyAll\n\t/home/ptab/corp/etcd/server/etcdserver/server.go:1105\ngo.etcd.io/etcd/server/v3/etcdserver.(*EtcdServer).run.func8\n\t/home/ptab/corp/etcd/server/etcdserver/server.go:1059\ngo.etcd.io/etcd/pkg/v3/schedule.(*fifo).run\n\t/home/ptab/corp/etcd/pkg/schedule/schedule.go:157"}
        panic: failed to update; member unknown
        
        goroutine 162 [running]:
        go.uber.org/zap/zapcore.(*CheckedEntry).Write(0xc0003ee300, 0xc0003ee540, 0x3, 0x3)
        	/home/ptab/private/golang/pkg/mod/go.uber.org/[email protected]/zapcore/entry.go:234 +0x58d
        go.uber.org/zap.(*Logger).Panic(0xc00007c300, 0x118827e, 0x20, 0xc0003ee540, 0x3, 0x3)
        	/home/ptab/private/golang/pkg/mod/go.uber.org/[email protected]/logger.go:226 +0x85
        go.etcd.io/etcd/server/v3/etcdserver/api/membership.(*RaftCluster).UpdateAttributes(0xc0004d0000, 0xca50e9357181d758, 0xc0003c2258, 0x18, 0xc000230080, 0x1, 0x1)

[jingyih]

LGTM

[jingyih]

Thanks! This was overlooked.

[codecov-io]

Codecov Report

Merging #12804 (cc0f812) into master (e24e72c) will decrease coverage by 19.56%.
The diff coverage is 12.50%.

@@             Coverage Diff             @@
##           master   #12804       +/-   ##
===========================================
- Coverage   65.14%   45.58%   -19.57%     
===========================================
  Files         421      401       -20     
  Lines       33024    33106       +82     
===========================================
- Hits        21514    15090     -6424     
- Misses       9415    16027     +6612     
+ Partials     2095     1989      -106     

Flag	Coverage Δ
all	45.58% <12.50%> (-19.57%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
client/v2/discover.go	0.00% <ø> (ø)
client/v2/keys.go	44.31% <ø> (-20.46%)	⬇️
client/v2/members.go	16.98% <ø> (-26.42%)	⬇️
client/v3/cluster.go	20.00% <ø> (-70.00%)	⬇️
client/v3/logger.go	38.09% <ø> (ø)
client/v3/snapshot/v3_snapshot.go	0.00% <ø> (-51.22%)	⬇️
etcdctl/ctlv2/command/backup_command.go	64.13% <0.00%> (-1.82%)	⬇️
etcdctl/ctlv2/command/role_commands.go	56.49% <ø> (ø)
etcdctl/ctlv2/command/util.go	42.76% <ø> (+2.51%)	⬆️
etcdctl/ctlv3/command/global.go	54.50% <ø> (ø)
... and 311 more

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