fix flaky test in comsumerTest

[zcai2]

Fixed flaky test that caused by ConsumerTest.java under skywaling-apm-datacarrier

Existing tests are flaky because the testConsumerMoreThanChannel doesn't clear channel at the beginning of this test case.

Both testConsumerLessThanChannel and testConsumerMoreThanChannel use the same carrier. In testConsumerLessThanChannel, it produces some data and store in the channel. When we run testConsumerMoreThanChannel, the data introduced by testConsumerLessThanChannel will affect this test case.

The flaky tests are found by running https://github.com/idflakies/iDFlakies

[codecov]

Codecov Report

Merging #5846 (3502df7) into master (8325824) will increase coverage by 0.05%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #5846      +/-   ##
============================================
+ Coverage     51.22%   51.27%   +0.05%     
+ Complexity     3461     3437      -24     
============================================
  Files          1654      911     -743     
  Lines         35436    22777   -12659     
  Branches       3861     2160    -1701     
============================================
- Hits          18151    11679    -6472     
+ Misses        16387    10156    -6231     
- Partials        898      942      +44     

Impacted Files	Coverage Δ	Complexity Δ
...g/oap/server/core/cluster/ClusterHealthStatus.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (ø%)
...ng/apm/agent/core/context/trace/LogDataEntity.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (ø%)
...p/server/core/analysis/metrics/MinLongMetrics.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (ø%)
...er/exporter/provider/grpc/GRPCExporterSetting.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (ø%)
...king/oap/server/configuration/api/ConfigTable.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (ø%)
...skywalking/oap/server/receiver/envoy/als/Role.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (ø%)
...r/receiver/envoy/als/k8s/ServiceNameFormatter.java	0.00% <0.00%> (-100.00%)	0.00% <0.00%> (ø%)
...alking/oap/server/core/cluster/OAPNodeChecker.java	0.00% <0.00%> (-93.75%)	0.00% <0.00%> (ø%)
...ent/core/context/status/ExceptionCheckContext.java	0.00% <0.00%> (-90.91%)	0.00% <0.00%> (ø%)
...t/status/HierarchyMatchExceptionCheckStrategy.java	9.09% <0.00%> (-90.91%)	1.00% <0.00%> (ø%)
... and 1147 more

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