Fix: Connection terminated unexpectedly error not caught in on error listener

[rchandranmani]

Our application was crashing when the database connection unexpectedly failed. This happened because:

1. We were previously using removeAllListeners('error'), which unintentionally removed the pg library's error handlers.
2. This left connection termination errors unhandled, leading to app crashes which uses this connector

We've fixed this by:

1. Completely removing the removeAllListeners('error') call within the connector. This ensures that the pg library's built-in error handling for connection issues remains active.
2. We now only add our connector's specific error listener if the pg client doesn't already have any error listeners attached (!pg.listenerCount('error')). This prevents us from creating too many listeners (addressing past MaxEventListeners warnings) while ensuring all critical connection errors are still properly managed.

Fixes #778
See also #746

Checklist

• DCO (Developer Certificate of Origin) signed in all commits
• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• Commit messages are following our guidelines

[aaqilniz]

Hi, @rchandranmani. Can you please fix the linting issues and the commit message?

You'd also need to add some tests around the changes you've made.