misc: Revert v21.2 specific commits for develop

These changes were made to the release staging branch for the v21.2
release. This commit reverts them for the develop branch.

Change-Id: I9f02470d00d5034a0797f32d4c1fe0e7055860a6
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54904
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

src/python/gem5/resources/downloader.py

@@ -45,7 +45,7 @@ def _resources_json_version_required() -> str:
     """
     Specifies the version of resources.json to obtain.
     """
-    return "21.2"
+    return "develop"
 
 def _get_resources_json_uri() -> str:
     uri = (