How do I avoid reimporting assetBundles when upgrading unity?

Lets assume I have 20,000 AssetsBundles of 100k size each. So, roughly 2 terabytes. These bundles will be served up as necessary by a CDN.

Sometimes when upgrading unity, all assets are reimported. I don't want unity to reimport all these assets.

From what I've seen with AssetsBundles, they are all inside of your assets folder. Is there a way to ignore the asset bundles? I would want the build machine to do heavy reimporting like that.

I want myself to act like a normal client and just receive assets as I need them.

Can i ignore reimporting AssetsBundles? Can I put the AssetsBundles into a seperate project? I want to completely separate downloaded content from shipped content (because there is so much of it)