Configuration of RPC for ironic-inspector was a bit of a mixed
bag, with some config fixed at defaults which are only relevant
for HA queues. This conforms it to the way the majority of
variables are managed.
Note that this changes the default for
ironic_inspector_oslomsg_rpc_use_ssl, but this should be set via
oslomsg_rpc_use_ssl anyway.
This also removes various unused inspector notification defaults.
Change-Id: I7edc658f57de5ffc6d4aa158b02d26fa3ad71c9d
3f7e851b98