Do not use 0.0.0.0 for client connection, use real hostname instead

[tashoyan]

Solves https://github.com/confluentinc/schema-registry/issues/1414

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[tashoyan]

@rayokota, @xiaoyali97 - would you like to review this PR? The modification is trivial, but it solves a quite annoying problem.

[tashoyan]

@rayokota @Clarence97 - would you review this PR please? It would be great to close this annoying issue.

[tashoyan]

[clabot:check]

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