Add an e2e case to verify cluster mode

[hanahmily]

• Tests(including UT, IT, E2E) are added to verify the new feature.

[codecov-commenter]

Codecov Report

Merging #335 (5f8d656) into main (4af513a) will increase coverage by 0.04%.
The diff coverage is 76.47%.

@@            Coverage Diff             @@
##             main     #335      +/-   ##
==========================================
+ Coverage   39.81%   39.86%   +0.04%     
==========================================
  Files         109      109              
  Lines       11872    11883      +11     
==========================================
+ Hits         4727     4737      +10     
  Misses       6680     6680              
- Partials      465      466       +1     

Files Changed	Coverage Δ
pkg/run/run.go	0.00% <0.00%> (ø)
banyand/metadata/client.go	43.42% <78.57%> (+3.28%)	⬆️
banyand/metadata/schema/etcd.go	50.92% <100.00%> (+0.18%)	⬆️
banyand/tsdb/buffer.go	68.57% <100.00%> (ø)

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