The generator will be responsible for spreading view updates with the
help of mutate_MV helper. The latter needs storage proxy to operate, so
the generator gets this dependency in advance.
There's no need to change start/stop order at the moment, generator
already starts after and stops before proxy. Also, services that have
generator as dependency are not required by proxy (even indirectly) so
no circular dependency is produced at this point.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>