etcd3 lookup - improve HTTPS connection handling and docs (#11861)
* etcd3 lookup - improve HTTPS connection handling and documentation
Improve user experience when connecting to HTTPS etcd3 endpoints:
- Strip URL scheme from host option when present, with a warning
- Warn when HTTPS endpoint is specified but ca_cert is not provided
- Document that ca_cert is required to enable TLS
- Add HTTPS connection example
- Fix minor doc markup issue in notes section
Fixes#1664
* Add changelog fragment for PR 11861
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(cherry picked from commit 076bc4e03b)
Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
