do not wait on deleted collections (#1953)

## Type of change

- [x] 🐛 Bugfix

## Issue(s)

* #1950

## Test Plan

- [x] 💪 Manual

src/internal/connector/data_collections.go

@@ -56,9 +56,17 @@ func (gc *GraphConnector) DataCollections(
 			return nil, err
 		}
 
-		for range colls {
+		for _, c := range colls {
+			// kopia doesn't stream Items() from deleted collections,
+			// and so they never end up calling the UpdateStatus closer.
+			// This is a brittle workaround, since changes in consumer
+			// behavior (such as calling Items()) could inadvertently
+			// break the process state, putting us into deadlock or
+			// panics.
+			if c.State() != data.DeletedState {
 				gc.incrementAwaitingMessages()
 			}
+		}
 
 		return colls, nil