test: show benchmark library help in addition to tclap when --help is specified. (#20085)
test: show benchmark library help in addition to tclap when --help is specified. (#20085)

Signed-off-by: Joshua Marantz <c3f6b7d9de5243f9f0884ee043fd42ff9df5f177@google.com>
envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy