fix: allow header propagation for router-plugins#2877

Noroth wants to merge 2 commits into

mainwundergraph/cosmo:mainfrom

ludwig/eng-9615-router-plugin-metadata-overwritten-in-grpc-plugin-middlewarewundergraph/cosmo:ludwig/eng-9615-router-plugin-metadata-overwritten-in-grpc-plugin-middlewareCopy head branch name to clipboard