Add sites to metadata path (#4169)

This makes the following change to the metadata path:

```diff
-tenant/groupsMetadata/resourceOwner/libraries
+tenant/groupsMetadata/resourceOwner/libraries/sites/site-id
```

The change only affect groups and no other services.
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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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- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [x] 🧹 Tech Debt/Cleanup

#### Issue(s)

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* #<issue>

#### Test Plan

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

src/internal/m365/collection/drive/group_handler.go

@@ -63,6 +63,11 @@ func (h groupBackupHandler) MetadataPathPrefix(tenantID string) (path.Path, erro
 		return nil, clues.Wrap(err, "making metadata path")
 	}
 
+	p, err = p.Append(false, odConsts.SitesPathDir, h.siteID)
+	if err != nil {
+		return nil, clues.Wrap(err, "appending sites to metadata path")
+	}
+
 	return p, nil
 }
 

src/internal/m365/collection/drive/group_handler_test.go

@@ -59,7 +59,7 @@ func (suite *GroupBackupHandlerUnitSuite) TestMetadataPathPrefix() {
 	}{
 		{
 			name:      "group",
-			expect:    "tenant/groupsMetadata/resourceOwner/libraries",
+			expect:    "tenant/groupsMetadata/resourceOwner/libraries/sites/site-id",
 			expectErr: assert.NoError,
 		},
 	}