Migrate SLO aware routing to implement prepare data hooks #1943
Description
Presently SloAwareRouting plugin doesn't implement prepare data plugin and rather relies on generating predictions in an imperative manner. Furthermore, it relies on cycle state which is a global state and it is to be deprecated in near future.
Instead, SLOAwareRouting should instead do the predictions in preparedata phase and get the prefix cache match score from attribute map present in the pod, for example
prefixCacheMatchScore, ok := pod.Get(plugins.PrefixCacheMatchPrecentKey)