## Description
Remove OwnersCats so only the Reason struct or tags pass information
between BackupOp and kopia
Instead of having a separate struct (OwnersCats) to fetch previous
snapshots, generate and use reasons. While this results in some repeated
data, it cuts down on the number of distinct structs and simplifies some
of the code for getting previous manifests.
A future PR should create a shared function to create a service/cat tag
given a reason.
Only pass in a set of tags to BackupCollections. This pushes the onus
of generating the tags for later snapshot lookups to BackupOp and
creates a somewhat asymmetric interface as Reason is used for the lookup
but tags is used for the backup. This will be updated later so that both
paths use a common function to convert from Reason->tags.
Despite that, it may result in a cleaner interface with kopia (depending
on how far we want to push it) where tags become the main mean of
communication.
## Does this PR need a docs update or release note?
- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No
## Type of change
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [x] 🧹 Tech Debt/Cleanup
## Issue(s)
* #1916
## Test Plan
- [x] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E
43c2017492