KServe: perform a canary rollout by splitting traffic between two InferenceService revisions

Steps

1. Deploy the first InferenceService revision normally; it receives 100% of traffic and KServe tracks it as the last good (LatestRolledoutRevision).
2. Update the InferenceService spec with the new model version (e.g. a new storageUri) and set canaryTrafficPercent on the component, e.g. `canaryTrafficPercent: 10`, to send that percentage of traffic to the new revision.
3. Re-apply the manifest with `kubectl apply`; KServe automatically splits traffic between the previously-promoted revision and the newly rolling-out revision according to canaryTrafficPercent.
4. To promote the canary, remove the canaryTrafficPercent field and re-apply — the new revision becomes the LatestRolledoutRevision and takes 100% of traffic.
5. To roll back, set canaryTrafficPercent to 0 (or re-apply the previous good spec) so 100% of traffic is pinned back to the PreviousRolledoutRevision.
6. Optionally add the serving.kserve.io/enable-tag-routing annotation to get tag-based URLs so you can explicitly hit the canary or the stable revision instead of relying only on the percentage split.