upload-to-storage: move directory instead of remove

this should hopefully bypass permission issues caused by the fact that
build runs as sudo but upload does not.

upload-to-storage.sh

@@ -5,7 +5,7 @@
 set -eu
 
 # Do not blow the lid off the storage for now. Reset the tree and only publish a select few files
-rm -rf upload-tree
+mv upload-tree upload-tree-old || true
 if [ ! -d upload-tree ]; then
     mkdir upload-tree
     for f in *.raw *.erofs *.efi; do