Allow IPv6 address with square brackets for webmock Zoekt

What does this MR do and why?

We found in https://dev.gitlab.org/gitlab/gitlab-ee/-/jobs/16571632 that the IP address can have square brackets around it and webmock allow won't be honored. So we need to add the same ip address again with square brackets so we support both cases.

In the end we've disabled ipv6 on our runners anyway because it wasn't working for other reasons but this change may still be useful in case we re-enable it.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.