Revert "fix: Create a subdirectory in the tmp directory"

This reverts commit 6540a6303f.

lib/utils/matrix_sdk_extensions/flutter_matrix_dart_sdk_database/builder.dart

@@ -65,12 +65,7 @@ Future<MatrixSdkDatabase> _constructDatabase(String clientName) async {
 
   Directory? fileStorageLocation;
   try {
-    final tmpDir = await getTemporaryDirectory();
-    final appTmpDir = Directory(join(tmpDir.path, clientName));
-    if (!await appTmpDir.exists()) {
-      await appTmpDir.create(recursive: true);
-    }
-    fileStorageLocation = appTmpDir;
+    fileStorageLocation = await getTemporaryDirectory();
   } on MissingPlatformDirectoryException catch (_) {
     Logs().w(
       'No temporary directory for file cache available on this platform.',