fix(se): handle EOF in stdin (#5486)
Turns out we didn't actually exit when we hit EOF in stdin in the schema
engine's RPC server, and just kept sleeping forever instead.
This commit changes that to drain the `client_adapter.request_receiver`
queue and exit the loop when EOF is encountered.
This is important because on Windows we can't use signals for graceful
shutdown, so we should do that by closing the stdin pipe.
Ref:
https://linear.app/prisma-company/issue/ORM-1093/schema-engine-termination-on-windows
