Simplify stable channel upgrade paths

1. Proposed title of this feature request: Simplify supported stable channel upgrade paths.
2. What is the nature and description of the request?

The recommended upgrade path for OpenShift 4.5 to OpenShift 4.6 should work any and all times for versions which exist in stable channel for both releases without forcing the upgrades.

For example:

4.4.old -> 4.4.stable.latest -> 4.5.stable.latest -> 4.6.stable.latest

3. Why does the customer need this? (List the business requirements here)

Customer wishes to handle updating via automation, and is concerned with not being able to run one-line updates without risk of ending at a z-stream without a path to next minor version.

Example: if I were on 4.3.35 and I did `oc adm upgrade -to-latest` and I was still on the fast/stable-4.3 channel, it would upgrade me to 4.3.38, which is totally fair game.  Customer would like an option such as `-to-latest-supported-edge` where if I'm on 4.3.35 and the fast/stable-4.3 channel, it won't upgrade me to 4.3.38 because that doesn't have a pathway to the next minor (4.4.x) - so I don't get stuck in a dead end.

4. List any affected packages or components.