g3-fluentd: parse retry_queue_len from yaml

[dajiaohuang]

Summary

• parse the documented retry_queue_len Fluentd YAML option as a usize
• pass the parsed value to the existing set_retry_queue_len configuration hook
• extend the Fluentd YAML parser test to verify the configured queue length

The three existing Fluentd driver pages already document this option, so no documentation source changes are needed.

Fixes #1118.

Testing

On Windows x86_64-pc-windows-msvc with Rust 1.97.0:

• cargo +1.97.0 fmt --all -- --check
• cargo +1.97.0 test -p g3-fluentd -p g3fcgen --features g3-fluentd/yaml,g3fcgen/vendored-aws-lc --locked (8 g3-fluentd tests passed; selected g3fcgen and doctest targets also passed)
• cargo +1.97.0 clippy -p g3-fluentd -p g3fcgen --features g3-fluentd/yaml,g3fcgen/vendored-aws-lc --all-targets --locked -- --deny warnings --allow clippy::useless_borrows_in_formatting
• git diff --check

The narrow Clippy allow is for the two unrelated upstream g3fcgen/g3-slog-types Rust 1.97 findings tracked in #1111 and fixed separately by #1112; g3-fluentd remains checked with warnings denied.

[zh-jq]

Good catch. Can you also submit a PR to https://github.com/VEY-OSS/vey?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.72%. Comparing base (ac4f482) to head (4e2e9fd).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1119      +/-   ##
==========================================
+ Coverage   67.69%   67.72%   +0.02%     
==========================================
  Files        1432     1432              
  Lines      136759   136766       +7     
==========================================
+ Hits        92573    92618      +45     
+ Misses      44186    44148      -38     

Flag	Coverage Δ
g3bench	19.76% <0.00%> (+<0.01%)	⬆️
g3keymess	20.75% <0.00%> (-0.01%)	⬇️
g3mkcert	26.73% <ø> (ø)
g3proxy	49.94% <0.00%> (+0.04%)	⬆️
g3statsd	5.58% <ø> (ø)
lib	57.87% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[dajiaohuang]

Submitted the corresponding VEY change as requested: VEY-OSS/vey#96