test: fix data races in FakeStream. (#7929)
test: fix data races in FakeStream. (#7929)

Fixes #7927.

Risk Level: low (test only)

Signed-off-by: Piotr Sikora <ba6f3a1a6d7e1ecae91b31e93969cc392fbd0fdd@google.com>

eklitzke/envoy,jrajahalme/envoy,envoyproxy/envoy,envoyproxy/envoy,eklitzke/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,eklitzke/envoy,lyft/envoy,jrajahalme/envoy,istio/envoy,envoyproxy/envoy,jrajahalme/envoy,envoyproxy/envoy-wasm,lizan/envoy,lizan/envoy,istio/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,lizan/envoy,jrajahalme/envoy,envoyproxy/envoy,istio/envoy,lyft/envoy,eklitzke/envoy,lyft/envoy,lyft/envoy,istio/envoy,lizan/envoy,eklitzke/envoy,lizan/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy,eklitzke/envoy,envoyproxy/envoy,istio/envoy,jrajahalme/envoy,lizan/envoy,istio/envoy,envoyproxy/envoy,istio/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,jrajahalme/envoy,envoyproxy/envoy