test: replace s3cmd calls with aws s3

Quick tests showed that the sync operation is much faster with awscli2
than with s3cmd.

test/scripts/imgtestlib.py

@@ -122,10 +122,9 @@ def dl_s3_configs(destination):
 
     print(f"⬇️ Downloading configs from {s3url}")
     # only download info.json (exclude everything, then include) files, otherwise we get manifests and whole images
-    job = sp.run(["s3cmd", *s3_auth_args(), "sync",
+    job = sp.run(["aws", "s3", "sync",
                   "--exclude=*",
-                  "--include=info.json",
-                  "--delete-removed",
+                  "--include=*/info.json",
                   s3url, destination],
                  capture_output=True,
                  check=False)

test/scripts/upload-results

@@ -46,7 +46,7 @@ def main():
     s3url = f"{bucket}/images/builds/{distro}/{arch}/{manifest_id}/"
 
     print(f"⬆️ Uploading {build_dir} to {s3url}")
-    testlib.runcmd(["s3cmd", *testlib.s3_auth_args(), "--acl-private", "put", "--recursive", build_dir+"/", s3url])
+    testlib.runcmd(["aws", "s3", "cp", "--acl=private", "--recursive", build_dir+"/", s3url])
     print("✅ DONE!!")