## Description
Use the check to see if a user has access to OneDrive/Exchange to also see if the user exists. This does not stop the population of GraphConnector users every time an instance is created, but does move us one step closer to that
Manually tested the following cases:
* backup "*"
* backup single existing user without error
* backup multiple existing users without error
* error when attempting to backup user that doesn't exist in the same domain
* error when attempting to backup user that doesn't exist in a different domain
Sample error output (progress disabled):
```text
No backups available
Error: 1 error occurred:
* Failed to run Exchange backup for user foo@other.onmicrosoft.com: doing backup: producing backup data collections: resource owner [foo@other.onmicrosoft.com] not found within tenant
```
## 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)
* #1547
## Test Plan
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E
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