quic: mark drain promise handled

[jasnell]

Fixes: #64290

@nodejs/quic @martenrichter

[nodejs-github-bot]

Review requested:

• @nodejs/quic

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/75874/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (86c871e) to head (39fa1e0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65319      +/-   ##
==========================================
- Coverage   90.12%   90.11%   -0.01%     
==========================================
  Files         752      752              
  Lines      251569   251571       +2     
  Branches    47267    47267              
==========================================
- Hits       226738   226715      -23     
- Misses      16184    16201      +17     
- Partials     8647     8655       +8     

Files with missing lines	Coverage Δ
lib/internal/quic/quic.js	100.00% <100.00%> (ø)

... and 31 files with indirect coverage changes

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[martenrichter]

lgtm Thanks!