Prefer to have operators use Envoy's native Zipkin tracer, since Zipkin
implies libcurl in opencensus. Once we complete a deprecation cycle
here, we should be able to remove this source of libcurl dependency.
Part of #11816.
Risk level: Low
Testing: bazel test //test/...
Signed-off-by: Harvey Tuch <htuch@google.com>
Mirrored from https://github.com/envoyproxy/envoy @ 877d8e1f4ddd52f7a4b7bdacd3f95529469de672