Quality reinforcement (14): fix unstable test cases

[lance6716]

previous one #1997

• [ ] ha_master https://github.com/pingcap/dm/issues/1762
• [ ] testElectionSuite.TestFailToStartLeader

[2021-08-10T03:55:24.792Z] election_test.go:91:
[2021-08-10T03:55:24.792Z]     c.Assert(leaderID, check.Equals, cfg1.Name)
[2021-08-10T03:55:24.792Z] ... obtained string = "dm-master-2"
[2021-08-10T03:55:24.792Z] ... expected string = "dm-master-1"

[2021-09-10T02:40:21.660Z] FAIL: election_test.go:34: testElectionSuite.TestFailToStartLeader
[2021-09-10T02:40:21.661Z] 
[2021-09-10T02:40:21.661Z] election_test.go:90:
[2021-09-10T02:40:21.661Z]     c.Assert(err, check.IsNil)
[2021-09-10T02:40:21.661Z] ... value *terror.Error = [code=11108:class=functional:scope=internal:level=medium], Message: fail to get leader ID, RawCause: context deadline exceeded ("[code=11108:class=functional:scope=internal:level=medium], Message: fail to get leader ID, RawCause: context deadline exceeded")

[2021-09-10T03:36:08.379Z] FAIL: election_test.go:34: testElectionSuite.TestFailToStartLeader
[2021-09-10T03:36:08.379Z] 
[2021-09-10T03:36:08.379Z] election_test.go:90:
[2021-09-10T03:36:08.379Z]     c.Assert(err, check.IsNil)
[2021-09-10T03:36:08.379Z] ... value *terror.Error = [code=11108:class=functional:scope=internal:level=medium], Message: fail to get leader ID, RawCause: context deadline exceeded ("[code=11108:class=functional:scope=internal:level=medium], Message: fail to get leader ID, RawCause: context deadline exceeded")

• [ ] testMaster.TestOfflineMember jenkins
• [ ] DM-UpdateBARule jenkins
• [ ] dmtl pause-relay jenkins
• [ ] master start too slowly jenkins jenkins jenkins jenkins jenkins jenkins jenkins jenkins good example #2095
• [ ] testScheduler.TestScheduler jenkins
• [ ] ha_cases jenkins
• [ ] testEtcdUtilSuite.TestEtcdUtil jenkins jenkins
• [ ] all_mode query-stauts takes too much time jenkins
• [ ] handle_error_2 DM-4215 jenkins
• [ ] import_goroutine_leak jenkins jenkins
• [ ] syncer.go WaitGroup data race https://github.com/pingcap/dm/blob/e008ef3e2d068da5c27e8df12700927d0f8719f7/syncer/syncer.go#L669 and inside s.Run there're many s.wg.Add
• [ ] TestShardDDL unit tests jenkins
• [ ] all_mode jenkins jenkins
• [ ] dmtl get task config jenkins
• [ ] checkpoint-transaction jenkins
• [ ] drop_column_with_index jenkins
• [ ] sequence_sharding_optimistic jenkins
• [ ] testMaster.TestCheckTask jenkins
• [ ] metrics jenkins

[2021-09-22T09:10:54.222Z] [2021/09/22 17:10:43.944 +08:00] [DEBUG] [baseconn.go:164] ["execute statement"] [task=test] [unit="binlog replication"] [query="INSERT INTO `metrics`.`t1` (`id`,`name`,`dt`,`ts`,`new_col1`) VALUES (?,?,?,?,?)"] [argument="[1004 zmj4 <nil> 2022-05-11 12:01:05 <nil>]"]
[2021-09-22T09:10:54.222Z] [2021/09/22 17:10:43.946 +08:00] [DEBUG] [syncer.go:1382] ["timer Reset"] [task=test] [unit="binlog replication"] [workerJobIdx=4] [tickerInterval=5s] ["current ts"=1632301843]

• [] testMaster.TestStartTaskWithRemoveMeta jenkins