Refs #21012 -- Removed unnecessary _create_cache() hook.

This removes unused (since d038c547b5)
workaround to load a cache backend with its dotted import path and
moves remaining logic to the CacheHandler.

Thanks Tim Graham for the review.

django/core/cache/__init__.py

@@ -29,31 +29,6 @@ __all__ = [
 DEFAULT_CACHE_ALIAS = 'default'
 
 
-def _create_cache(backend, **kwargs):
-    try:
-        # Try to get the CACHES entry for the given backend name first
-        try:
-            conf = settings.CACHES[backend]
-        except KeyError:
-            try:
-                # Trying to import the given backend, in case it's a dotted path
-                import_string(backend)
-            except ImportError as e:
-                raise InvalidCacheBackendError("Could not find backend '%s': %s" % (
-                    backend, e))
-            location = kwargs.pop('LOCATION', '')
-            params = kwargs
-        else:
-            params = {**conf, **kwargs}
-            backend = params.pop('BACKEND')
-            location = params.pop('LOCATION', '')
-        backend_cls = import_string(backend)
-    except ImportError as e:
-        raise InvalidCacheBackendError(
-            "Could not find backend '%s': %s" % (backend, e))
-    return backend_cls(location, params)
-
-
 class CacheHandler:
     """
     A Cache Handler to manage access to Cache instances.
@@ -75,8 +50,16 @@ class CacheHandler:
             raise InvalidCacheBackendError(
                 "Could not find config for '%s' in settings.CACHES" % alias
             )
-
+        params = settings.CACHES[alias].copy()
-        cache = _create_cache(alias)
+        backend = params.pop('BACKEND')
+        location = params.pop('LOCATION', '')
+        try:
+            backend_cls = import_string(backend)
+        except ImportError as e:
+            raise InvalidCacheBackendError(
+                "Could not find backend '%s': %s" % (backend, e)
+            )
+        cache = backend_cls(location, params)
         self._caches.caches[alias] = cache
         return cache