test: Replace external registry deps with mock server in search tests

- Add comprehensive mock registry server for e2e search tests
- Replace quay.io and other external registry calls with local mock
- Improve test reliability by removing network dependencies
- Maintain full test coverage with controlled mock data

Fixes: #27304
Fixes: https://issues.redhat.com/browse/RUN-3623

Signed-off-by: Jan Rodák <[email protected]>

Author: Honny1