fix(router): close multipart heartbeat connections after subscription closes#1527

df-wg wants to merge 1 commit intomainwundergraph/cosmo:mainfrom

dave/eng-6234-multipart-write-error-when-router-loses-its-connection-withwundergraph/cosmo:dave/eng-6234-multipart-write-error-when-router-loses-its-connection-withCopy head branch name to clipboard