Importing more content (or deleting resources) to a channel undoes its original position in channel list
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### Observed behavior

~Similar to #5292, if you import more content to a channel, it will always be moved to the bottom of the Device > Channel page even if you had given it a different order (or didn't reorder it but just imported it in the past at some point). Because a lot of places in the app use the same order, we also see #5292~

Edit: This has been resolved for Kolibri when using Sqlite, but when using Postgresl, what seems to happen is that the newly modified channel goes to the _top_ of the list. It's because the channel in this case falls into this branch:

https://github.com/learningequality/kolibri/blob/0ee38838e5fc74d1f85b15c867f53ec4c261448c/kolibri/core/content/utils/annotation.py#L479-L482

~A somewhat mitigating factor is that newly updated channels will temporarily be moved to the top of the channel and have a green "New" label attached to it, so it will be easy to find immediately after the import.~

### Expected behavior

Updating a channel doesn't move it to the ~"bottom"~ top of the channel list.

### User-facing consequences

1. Users will need to move the channel again
1. Users might not immediately realize the channel moved 

### Errors and logs
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…

### Steps to reproduce
1. Run Kolibri using Postgresql as DB
1. Run a similar scenario as described above

### Context
Kolibri 0.13
diff --git a/kolibri/core/content/utils/annotation.py b/kolibri/core/content/utils/annotation.py
index f06a9c1e09..c2c6f3d092 100644
--- a/kolibri/core/content/utils/annotation.py
+++ b/kolibri/core/content/utils/annotation.py
@@ -478,6 +478,8 @@ def calculate_next_order(channel, model=ChannelMetadata):
     latest_order = model.objects.latest("order").order
     if latest_order is None:
         channel.order = 1
-    else:
+
+    if channel.order is None or channel.order == 0:
         channel.order = latest_order + 1
+
     channel.save()
['kolibri/core/content/utils/annotation.py']