fix: use pre-increment for request counter

[BrainTR]

This relates to...

Rationale

When the maxRequestsPerClient option is set, using post-increment on the request counter causes one extra request before the connection is closed.

Changes

Features

Bug Fixes

Breaking Changes and Deprecations

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

[mcollina]

Thanks, can you add a test for this?

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.03%. Comparing base (bc0a19c) to head (f68bd53).
⚠️ Report is 15 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5033   +/-   ##
=======================================
  Coverage   93.03%   93.03%           
=======================================
  Files         110      110           
  Lines       35793    35793           
=======================================
  Hits        33301    33301           
  Misses       2492     2492           

☔ View full report in Codecov by Sentry.
📢 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.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[BrainTR]

One of test added in #5034 covers the maxRequestsPerClient parameter. Since it also includes my changes, this PR can be closed once that one is merged.