Update registry1.dso.mil/ironbank/elastic/eck-operator/eck-operator Docker tag to v2.16.0

This MR contains the following updates:

Package	Update	Change
registry1.dso.mil/ironbank/elastic/eck-operator/eck-operator (source)	minor	2.15.0 -> 2.16.0

Complete MR checklist

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• Followed upgrade instructions outlined in docs/DEVELOPMENT_MAINTENANCE.md
• Update Docs with new/updated steps as needed
• Tested and Validated Changes made with supporting info like logs or screenshots from test pipelines

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• Tested and Validated changes

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Upgrade Notices

• NOTE: Will redeploy ES/Kibana cluster upon upgrade