fix: race condition when querying registered operators data

[ricomateo]

What Changed?

This PR adds a small fix for a race condition found when querying registered operators data.

The functions QueryExistingRegisteredOperatorPubKeys and QueryExistingRegisteredOperatorSockets both run in parallel and they read and mutate the same variable startBlock. This causes a race condition because startBlock is a *big.Int.

The solution is to clone the startBlock into a new variable for each function.

A better solution would be to change QueryExistingRegisteredOperatorPubKeys and QueryExistingRegisteredOperatorSockets function signatures to receive startBlock as primitive int64 variable instead of *big.Int and do the conversion to *big.Int inside of the functions.

Reviewer Checklist

• Code is well-documented
• Code adheres to Go naming conventions
• Code deprecates any old functionality before removing it

[samlaf]

Thanks for this fix :) Let's just add a comment to explain why we are doing this.

[samlaf]

LGTM thanks! operator unit test is failing, we know why. Will push a fix soon and then you'll just have to rebase on top before merging this PR.