fix(go,csharp): remove duplicate consumer groups in DeserializeClient/MapClient

[atharvalade]

Which issue does this PR close?

Closes #3131

Rationale

DeserializeClient (Go) and MapClient (C#) return duplicate/zero-valued consumer groups due to incorrect slice pre-allocation and a redundant outer loop.

What changed?

In Go, make([]ConsumerGroupInfo, Count) pre-allocated Count zero-valued entries, then append added real data after them—doubling the slice. The outer for position < length loop could also re-read groups if trailing bytes existed.

Fixed both SDKs by using make([], 0, Count) (Go) / new List<>(Count) (C#) for correct capacity-only allocation, and replaced the outer while/for loop with a single bounded for i < Count pass.

Local Execution

• Passed
• Pre-commit hooks ran

AI Usage

1. Opus 4.6
2. Minimal AI used
3. Verified via go build, go vet, go test, dotnet build, dotnet test (100/100 passed), and CI lint scripts
4. Yes, all code can be explained

[codecov]

Codecov Report

❌ Patch coverage is 56.00000% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.77%. Comparing base (7de9d09) to head (149c31a).

Files with missing lines	Patch %	Lines
...nary_serialization/binary_response_deserializer.go	0.00%	11 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3164      +/-   ##
============================================
- Coverage     73.61%   72.77%   -0.85%     
  Complexity      943      943              
============================================
  Files          1141     1117      -24     
  Lines        100869    96105    -4764     
  Branches      78043    73303    -4740     
============================================
- Hits          74254    69939    -4315     
+ Misses        23958    23605     -353     
+ Partials       2657     2561      -96     

Components	Coverage Δ
Rust Core	73.55% <ø> (-1.03%)	⬇️
Java SDK	62.30% <ø> (ø)
C# SDK	69.11% <100.00%> (-0.30%)	⬇️
Python SDK	81.43% <ø> (ø)
Node SDK	91.40% <ø> (-0.04%)	⬇️
Go SDK	39.43% <0.00%> (+0.01%)	⬆️

Files with missing lines	Coverage Δ
foreign/csharp/Iggy_SDK/Mappers/BinaryMapper.cs	91.69% <100.00%> (-1.10%)	⬇️
...nary_serialization/binary_response_deserializer.go	83.57% <0.00%> (+0.40%)	⬆️

... and 86 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[lukaszzborek]

approve for csharp
for go looks the same 😅, but not sure about how tests looks like. Now there is no tests for that part