As described here:
#10379 (comment)

This affects the debug adapter factory. Currently, it looks at "pid" to determine whether an "attach" configuration should spawn the adapter, or connect to it using the specified "host" and "port". The first change needed here is to also spawn the debug adapter if it sees "listen". Secondly, when connecting using a socket, it needs to look for "host" and "port" inside "connect" first, and only then fall back to top-level properties.