Remove --enable-permissions-backup flag from sanity tests (#3020)

Permissions backup is now default, but this flag was never removed from sanity-tests CI.

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#### 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

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- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
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#### Test Plan

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- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

.github/workflows/sanity-test.yaml

@@ -237,7 +237,6 @@ jobs:
           ./corso backup create onedrive \
           --hide-progress \
           --user "${CORSO_M365_TEST_USER_ID}" \
-          --enable-permissions-backup \
           --json \
           2>&1 | tee $TEST_RESULT/backup_onedrive.txt 
 
@@ -308,7 +307,6 @@ jobs:
           ./corso backup create onedrive \
           --hide-progress \
           --user "${CORSO_M365_TEST_USER_ID}" \
-          --enable-permissions-backup \
           --json \
           2>&1 | tee $TEST_RESULT/backup_onedrive_incremental.txt