Remove search term separators

Relates #7656 in ansible-tower.

We have been using comma `,` and space ` ` to separate search terms in
query string `<field_name>__search=<search terms>`, however in general
we can always use `&` to achieve separation like
`<field_name>__search=<search term 1>&<field_name>__search=<search term
2>&...`. Using specific delimiters makes it impossible for search terms
to contain those delimiters, so they are better off being removed.

Signed-off-by: Aaron Tan <jangsutsr@gmail.com>

awx/api/filters.py

@@ -242,11 +242,10 @@ class FieldLookupBackend(BaseFilterBackend):
                 # Search across related objects.
                 if key.endswith('__search'):
                     for value in values:
-                        for search_term in force_text(value).replace(',', ' ').split():
-                            search_value, new_keys = self.value_to_python(queryset.model, key, search_term)
-                            assert isinstance(new_keys, list)
-                            for new_key in new_keys:
-                                search_filters.append((new_key, search_value))
+                        search_value, new_keys = self.value_to_python(queryset.model, key, force_text(value))
+                        assert isinstance(new_keys, list)
+                        for new_key in new_keys:
+                            search_filters.append((new_key, search_value))
                     continue
 
                 # Custom chain__ and or__ filters, mutually exclusive (both can

awx/api/templates/api/_list_common.md

@@ -60,6 +60,10 @@ _Added in AWX 1.4_
 
     ?related__search=findme
 
+Note: If you want to provide more than one search terms, please use multiple
+search fields with the same key, like `?related__search=foo&related__search=bar`,
+All search terms with the same key will be ORed together.
+
 ## Filtering
 
 Any additional query string parameters may be used to filter the list of