Emit request errors after aborted requests

[puneetdixit200]

Summary:

• emit the public request error event when a late 500 error is produced after an aborted request has already finalized
• reuse the same error-response logging helper for normal finalize and completed-response paths
• add a regression test for a handler that throws after the client disconnects

Tests:

• npm_config_cache=/tmp/hapi-npm-cache npx lab -a @hapi/code -m 5000 test/request.js -g "emits request-error when handler fails after abort|does not fail on abort|emits request-error once"
• source ~/.nvm/nvm.sh && nvm use 18.20.8 >/dev/null && npm_config_cache=/tmp/hapi-npm-cache npx lab -a @hapi/code -m 5000 test/request.js -g "emits request-error when handler fails after abort|does not fail on abort|emits request-error once"
• git diff --check

Fixes #4567