Actions Missing?

You do get asked when you install a new version. A popup comes up with two checkboxes - one to remove old versions, and one to migrate settings.

However, you only see this when you manually initiate the update. So you need to disable automatic updates in the CC app.

You save out (and reload) actions from the fly-out menu in the panel. Always do that. You can save them anywhere you want.

My recommendation is to not migrate settings. Preferences are prone to accumulating corruption because they are rewritten on every application exit, as opposed to read-only program files. Corrupt preferences contain the entire app configuration. The problem with corrupt preferences is that they are usually not recognized as such. They tend to just give unpredictable and weird behavior, and then people assume application bugs.

You can use Adobe feedback site to  give them ideas for improving Photoshop.  However, I don't think in this case they will think aromatic saving actions would be a good idea.  Images you work on are not automatic saved with each change you make. Humans make mistakes and like to experiment  with things and only save what they want to keep.  Users also change action and images  etc that are not their to change.  Anything you do the you want to keep you should save your own copy of, Image, actions, script, brushes, presets, etc.  How would Adobe know when they are correct or where you would want to save your assets.   Currently Adobe save your work on actions in your Actions Palette  Preferences.  When you are stratified they are what you want you should save you own Action Sets.  I would suggest not using any folder created by adobe.  That way you will know where all your Photoshop add ons are and you will not loose them should Adobe or you decide to uninstall some version of Photoshop. I have been doing this for 20 years+. Without problems.