CMakeLists.txt: fix status message for swift-collections (#1435)

The current configuration status message is quite confusing:
```
-- _SwiftCollections_SourceDIR provided, using swift-foundation-icu checkout at 
```
which clearly should be
```
-- _SwiftCollections_SourceDIR provided, using swift-collections checkout at 
```

Author: MaxDesiatov

CMakeLists.txt

@@ -79,7 +79,7 @@ else()
 endif()
 
 if (_SwiftCollections_SourceDIR)
-    message(STATUS "_SwiftCollections_SourceDIR provided, using swift-foundation-icu checkout at ${_SwiftCollections_SourceDIR}")
+    message(STATUS "_SwiftCollections_SourceDIR provided, using swift-collections checkout at ${_SwiftCollections_SourceDIR}")
     FetchContent_Declare(SwiftCollections
         SOURCE_DIR ${_SwiftCollections_SourceDIR})
 else()