[INLONG-788]Fix Go SDK Remote Cache Bug

[TszKitLo40]

Fixes Jira Issue ID:
https://issues.apache.org/jira/browse/INLONG-788

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• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

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[TszKitLo40]

@gosonzhang @charlely PTAL

[codecov-commenter]

Codecov Report

Merging #586 (69c29fb) into INLONG-25 (f711a68) will increase coverage by 0.02%.
The diff coverage is n/a.

@@              Coverage Diff               @@
##             INLONG-25    #586      +/-   ##
==============================================
+ Coverage         7.48%   7.51%   +0.02%     
  Complexity         479     479              
==============================================
  Files              267     267              
  Lines            29500   29500              
  Branches          4843    4843              
==============================================
+ Hits              2209    2216       +7     
+ Misses           26816   26810       -6     
+ Partials           475     474       -1     

Impacted Files	Coverage Δ
.../java/org/apache/flume/sink/tubemq/TubemqSink.java	55.42% <0.00%> (+4.00%)	⬆️

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[gosonzhang]

+1

[charlely]

Need check pos is Last.
if len(r.indexPartitions) == 1 && pos == 0 {
r.indexPartitions = nil // Because always use append to add item.
}
if pos >= 0 {
....
}