Backport of Support go-sockaddr templates in top-level cluster_addr config into release/1.9.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #13678 to be assessed for backporting due to the inclusion of the label backport/1.9.x.

WARNING automatic cherry-pick of commits failed. Commits will require human attention.

The below text is copied from the body of the original PR.

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In doing some testing I found that the listener clusteraddr isn't really used, or at least isn't as important as the top-level clusteraddr setting. As such, go-sockaddr templating needs to be implemented for the top-level cluster_addr setting or it's unusable for HA.

Also fix a nil pointer panic I discovered at the same time.

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