Add validation on params for Kubernetes and Elasticsearch PodLogs

What does this MR do?

Fixes Issue: #211509 (closed)

As per @akohlbecker's comment: #211509 (comment 328327959) I've added regex validation for DNS Subdomain Name.

Refer here for more context.

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Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
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