Remove pre-icehouse rpc client API compat

The compute rpc API was at version 3.23 for the Icehouse release.
Since we only support live upgrades from N-1 to N (Icehouse to Juno),
we can remove old rpc client support for versions that were
pre-Icehouse release.  This patch does that for the compute rpcapi.

Change-Id: Ice20b141dbe28de02e125fa5ced1dbc286ba2ee3
Merge "Remove pre-icehouse rpc client API compat"