feat(metarepos): ignore invalid report

[hungryjang]

What this PR does

This patch allows the metadata repository to ignore invalid reports from storagenode. Since storagenode is changed
not to save the commit context, an invalid report may be given in the learning state.

Which issue(s) this PR resolves

Updates #125

Anything else

Include any links or documentation that might be helpful for reviewers.

[codecov-commenter]

Codecov Report

Base: 62.85% // Head: 63.02% // Increases project coverage by +0.17% 🎉

Coverage data is based on head (2bcf5fc) compared to base (0a14ab5).
Patch coverage: 45.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #163      +/-   ##
==========================================
+ Coverage   62.85%   63.02%   +0.17%     
==========================================
  Files         126      126              
  Lines       17061    17075      +14     
==========================================
+ Hits        10723    10762      +39     
+ Misses       5781     5765      -16     
+ Partials      557      548       -9     

Impacted Files	Coverage Δ
proto/snpb/log_stream_reporter.go	0.00% <0.00%> (ø)
internal/metarepos/report_collector.go	77.85% <10.00%> (-0.43%)	⬇️
...metarepos/dummy_storagenode_client_factory_impl.go	64.62% <100.00%> (+2.12%)	⬆️
internal/metarepos/raft_metadata_repository.go	71.98% <100.00%> (+0.31%)	⬆️
internal/metarepos/storage.go	81.06% <0.00%> (+1.40%)	⬆️
internal/storagenode/replication_server.go	83.00% <0.00%> (+6.00%)	⬆️

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[ijsong]

Thank you for your commit.