Don't try to fetch backup version if no compete backups available (#3230)

Regression from 62daf10213 (diff-f088d3a5f56348ddaf6fbf485c2aeaa6d8b40a860de014f7084db6daf0753829R267)


---

#### 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

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/internal/operations/backup.go

@@ -243,6 +243,7 @@ func (op *BackupOperation) do(
 	var (
 		reasons           = selectorToReasons(op.Selectors, false)
 		fallbackReasons   = makeFallbackReasons(op.Selectors)
+		lastBackupVersion = version.NoBackup
 	)
 
 	logger.Ctx(ctx).With(
@@ -264,10 +265,12 @@ func (op *BackupOperation) do(
 		return nil, clues.Wrap(err, "producing manifests and metadata")
 	}
 
-	_, lastBackupVersion, err := lastCompleteBackups(ctx, op.store, mans)
+	if canUseMetaData {
+		_, lastBackupVersion, err = lastCompleteBackups(ctx, op.store, mans)
 		if err != nil {
 			return nil, clues.Wrap(err, "retrieving prior backups")
 		}
+	}
 
 	cs, excludes, err := produceBackupDataCollections(
 		ctx,