fix(benchmark): refine the benchmark tool for log subscription

[ijsong]

What this PR does

This update fixes the benchmark tool, enabling it to subscribe to all logs from
specified a topic or a log stream. It introduces a mechanism where a loader
fetches logs, with the number of logs defined by the "--subscribe-size" CLI
flag.

[ijsong]

Current dependencies on/for this PR:

• perf(client): use transmitResultPool to reduce heap allocs #722
• perf(client): prealloc pkg/varlog.(*transmitter).transmitQueue #721
• perf(client): optimize with atomic.Int64 for lastSubscribeAt in pkg/varlog.(subscriber) #720
• perf(client): reuse snpb.SubscribeResponse in RPC handler #719
• perf(benchmark): use grpc.SharedBufferPool for grpc.DialOption #718
• feat(benchmark): use gops to diagnose benchmark tool #717
• fix(benchmark): refine the benchmark tool for log subscription #716 👈
• perf(storage): improve scanning with GLSN #715
• test(storage): add benchmark for scanning with GLSN #714
• main

This stack of pull requests is managed by Graphite.

[codecov]

Codecov Report

Attention: Patch coverage is 19.16667% with 97 lines in your changes are missing coverage. Please review.

Project coverage is 49.80%. Comparing base (9f9401c) to head (9199784).
Report is 2 commits behind head on main.

❗ Current head 9199784 differs from pull request most recent head 01bf188. Consider uploading reports for the commit 01bf188 to get more accurate results

Files	Patch %	Lines
internal/benchmark/loader.go	0.00%	82 Missing ⚠️
internal/storage/scanner.go	71.87%	6 Missing and 3 partials ⚠️
internal/benchmark/benchmark.go	0.00%	4 Missing ⚠️
cmd/benchmark/test_command.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #716      +/-   ##
==========================================
+ Coverage   49.78%   49.80%   +0.02%     
==========================================
  Files         235      235              
  Lines       20651    20704      +53     
==========================================
+ Hits        10281    10312      +31     
- Misses       9730     9758      +28     
+ Partials      640      634       -6     

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[ijsong]

Merge activity

• Feb 26, 10:00 AM EST: @ijsong started a stack merge that includes this pull request via Graphite.
• Feb 26, 10:09 AM EST: Graphite rebased this pull request as part of a merge.
• Feb 26, 10:17 AM EST: @ijsong merged this pull request with Graphite.