Prior to this commit, the (happy path) shutdown sequence of an IOx
process was hard coded to:
1. Stop gRPC & HTTP servers
2. Stop backend server (i.e. ingester2)
After this commit, the execution of step 1 is delegated to the handler
for step 2; the server implementation (router / ingester / querier /
etc) now chooses when to shut down the RPC & HTTP servers.
This allows the server shutdown delegate to correctly sequence the
shutdown of all components of the IOx server. This allows ingester2 to
correctly sequence the shutdown of the query RPC server w.r.t the
graceful stop & persist, ensuring queries continue to be serviced.
Carol (Nichols || Goulding)
Andrew Lamb
Dom Dwyer
Andrew Lamb