Update Gitaly client dependency to include DNS lookup change (backport 17.8)

What does this MR do and why?

Gitaly currently uses the deprecated grpc.DialContext, which requires dns: prefixes for DNS resolution. However, tls: addresses lose DNS resolution because the dns: prefix is stripped. This creates issues when connecting to hostnames over TLS.

The new grpc.NewClient solves this by enabling DNS resolution by default, even without dns: prefixes. For example, tls://mygitalynode.test:1234 will now correctly resolve DNS. Only addresses with a DNS authority still require dns:.

This commit replaces grpc.DialContext with grpc.NewClient to simplify connection handling and fix the DNS resolution issue. Since Gitaly wraps gRPC connection logic, the change only needs to be made in one place.

Update Gitaly client dependency to include DNS lookup change

In gitaly!7693 (merged), Gitaly backports this change. This MR manually updates the workhorse's Gitaly client dependency to include that change.

See gitaly#6674 (closed) for details.

Related: Update workhorse's Gitaly client dependency to ... (!184525 - merged)

MR acceptance checklist

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

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The MR that fixed the bug on the default branch has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
• Set the milestone of the merge request to match the target backport branch version.
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the e2e:test-on-omnibus-ee job has either succeeded or been approved by a Software Engineer in Test.

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).