Minor cleanup to mail resolver fetch (#2808)

Remove old code that explicitly fetched the Inbox. The issue in Graph SDK that was causing this is no longer present.

Retrieval of Inbox is tested by [test](41f0b86073/src/internal/connector/exchange/data_collections_test.go (L235)) for making collections

---

#### 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)

* #2486

#### Test Plan

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

src/internal/connector/exchange/mail_folder_cache.go

@@ -38,28 +38,23 @@ func (mc *mailFolderCache) init(
 
 // populateMailRoot manually fetches directories that are not returned during Graph for msgraph-sdk-go v. 40+
 // rootFolderAlias is the top-level directory for exchange.Mail.
-// DefaultMailFolder is the traditional "Inbox" for exchange.Mail
 // Action ensures that cache will stop at appropriate level.
 // @error iff the struct is not properly instantiated
 func (mc *mailFolderCache) populateMailRoot(ctx context.Context) error {
-	for _, fldr := range []string{rootFolderAlias, DefaultMailFolder} {
-		var directory string
+	f, err := mc.getter.GetContainerByID(ctx, mc.userID, rootFolderAlias)
+	if err != nil {
+		return clues.Wrap(err, "fetching root folder")
+	}
 
-		f, err := mc.getter.GetContainerByID(ctx, mc.userID, fldr)
-		if err != nil {
-			return clues.Wrap(err, "fetching root folder")
-		}
-
-		if fldr == DefaultMailFolder {
-			directory = DefaultMailFolder
-		}
-
-		temp := graph.NewCacheFolder(f,
-			path.Builder{}.Append(directory), // storage path
-			path.Builder{}.Append(directory)) // display location
-		if err := mc.addFolder(temp); err != nil {
-			return clues.Wrap(err, "adding resolver dir").WithClues(ctx)
-		}
+	temp := graph.NewCacheFolder(
+		f,
+		// Root folder doesn't store any mail messages so it isn't given any paths.
+		// Giving it a path/location would cause us to add extra path elements that
+		// the user doesn't see in the regular UI for Exchange.
+		path.Builder{}.Append(), // storage path
+		path.Builder{}.Append()) // display location
+	if err := mc.addFolder(temp); err != nil {
+		return clues.Wrap(err, "adding resolver dir").WithClues(ctx)
 	}
 
 	return nil