Evaluate value of creating a new model to track entry/exit points and potentially impermanent critical tracking information

The following discussion from !12117 (merged) should be addressed:

• @minac started a discussion:

  issue: Pipelines can be deleted from the database 😞

It's possible we may need to track some of the important characteristics we want to keep from the pipeline directly to avoid their loss should the pipeline information be removed.

Additionally, due to some further discussion, it may be necessary to track this information separately from vulnerability_state_transitions as those are generally meant to be representative of user interaction and policy.