fix: Fix PoolConnection.end() callback and promise resolution

[CodeVoyager-bit]

This PR fixes an issue where calling end() on a PoolConnection would not execute the provided callback or resolve the promise when using the Promise API.

Previously, PoolConnection.end() did not accept any arguments, causing the callback to be ignored and the Promise wrapper to hang indefinitely.

Changes

• Updated PoolConnection.prototype.end to accept a callback parameter.
• Ensure callback is executed after releasing the connection back to the pool (when gracefulEnd is false).
• Pass callback to super.end() when gracefulEnd is true.

Related Issue

Fixes #3915

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.77%. Comparing base (9e8f539) to head (498574b).

Files with missing lines	Patch %	Lines
lib/base/pool_connection.js	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3937      +/-   ##
==========================================
- Coverage   89.78%   89.77%   -0.02%     
==========================================
  Files          86       86              
  Lines       13607    13610       +3     
  Branches     1607     1608       +1     
==========================================
+ Hits        12217    12218       +1     
- Misses       1390     1392       +2     

Flag	Coverage Δ
compression-0	88.88% <60.00%> (-0.02%)	⬇️
compression-1	89.75% <60.00%> (-0.02%)	⬇️
static-parser-0	87.34% <60.00%> (-0.02%)	⬇️
static-parser-1	88.11% <60.00%> (-0.02%)	⬇️
tls-0	89.17% <60.00%> (-0.02%)	⬇️
tls-1	89.54% <60.00%> (-0.02%)	⬇️

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[wellwelwel]

Thanks, @CodeVoyager-bit! Can you add a variation with this fix in the test test/integration/graceful-end/test-end-with-graceful-end-config.test.cjs?

About the lint error, you can run the command npm run lint:fix to fix it 🙋🏻‍♂️

[CodeVoyager-bit]

@wellwelwel can you please review it once

[wellwelwel]

This part is not being reached by the tests, I'm thinking of some approach to ensure continuity of this fix in the tests.