test: add integration test for XFF parsing (#3623)
test: add integration test for XFF parsing (#3623)

This should catch some regressions related to XFF parsing, like what's
described in #3607.

Signed-off-by: Raul Gutierrez Segales <f25f6873bbbde69f1fe653b3e6bd40d543b8d0e0@pinterest.com>
istio/envoy,lyft/envoy,eklitzke/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,jrajahalme/envoy,jrajahalme/envoy,lyft/envoy,envoyproxy/envoy-wasm,dnoe/envoy,lizan/envoy,envoyproxy/envoy,eklitzke/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,dnoe/envoy,envoyproxy/envoy-wasm,jrajahalme/envoy,lyft/envoy,jrajahalme/envoy,lizan/envoy,envoyproxy/envoy,istio/envoy,envoyproxy/envoy,dnoe/envoy,dnoe/envoy,lyft/envoy,eklitzke/envoy,lyft/envoy,lizan/envoy,envoyproxy/envoy,istio/envoy,eklitzke/envoy,lizan/envoy,istio/envoy,envoyproxy/envoy,istio/envoy,istio/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,jrajahalme/envoy,envoyproxy/envoy,envoyproxy/envoy,istio/envoy,dnoe/envoy,eklitzke/envoy,jrajahalme/envoy,eklitzke/envoy,lyft/envoy,lizan/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,lizan/envoy