Update test fixture instructions for import/export dev doc

doc/development/import_export.md

@@ -339,14 +339,13 @@ Fixtures used in Import/Export specs live in `spec/fixtures/lib/gitlab/import_ex
 There are two versions of each of these fixtures:
 
 - A human readable single JSON file with all objects, called either `project.json` or `group.json`.
-- A tree.tar.gz file containing a tree of files in `ndjson` format. **Please do not edit this file manually unless strictly necessary.**
+- A folder named `tree`, containing a tree of files in `ndjson` format. **Please do not edit files under this folder manually unless strictly necessary.**
 
 The tools to generate the NDJSON tree from the human-readable JSON files live in the [`gitlab-org/memory-team/team-tools`](https://gitlab.com/gitlab-org/memory-team/team-tools/-/blob/master/import-export/) project.
 
 ### Project
 
 **Please use `legacy-project-json-to-ndjson.sh` to generate the NDJSON tree.**
-Once you're done generating the files, please package them using `tar -czf tree.tar.gz tree` from the same directory as the `tree` directory generated is located.
 
 The NDJSON tree will look like this:
 
@@ -380,10 +379,7 @@ tree
 
 ### Group
 
-**Please use `legacy-group-json-to-ndjson.rb` to generate the NDJSON tree.** This script can be found in [`gitlab-org/memory-team/team-tools!7`](https://gitlab.com/gitlab-org/memory-team/team-tools/-/merge_requests/7).
-Once this MR is merged, the script will be found in the directory mentioned earlier.
-
-Once you're done generating the files, please package them using `tar -czf tree.tar.gz tree` from the same directory as the `tree` directory generated is located.
+**Please use `legacy-group-json-to-ndjson.rb` to generate the NDJSON tree.**
 
 The NDJSON tree will look like this:
 
@@ -409,4 +405,4 @@ tree
     └── 4352.json
 ```
 
-CAUTION: **Caution:** When updating these fixtures, please ensure you update the `json` files and the `tar.gz` archives, as the tests apply to both.
+CAUTION: **Caution:** When updating these fixtures, please ensure you update both `json` files and `tree` folder, as the tests apply to both.