build(drag-drop): clean up bazel config (#13934)

Removes the `sass_binary` since we don't ship CSS with `cdk/drag-drop` anymore and removes `cdk/overlay` from the dependencies.

Author: crisbeto

src/cdk/drag-drop/BUILD.bazel

@@ -1,6 +1,5 @@
 package(default_visibility=["//visibility:public"])
 
-load("@io_bazel_rules_sass//sass:sass.bzl", "sass_binary")
 load("//tools:defaults.bzl", "ng_module", "ng_test_library", "ng_web_test_suite")
 
 ng_module(
@@ -13,7 +12,7 @@ ng_module(
     "@rxjs",
     "@rxjs//operators",
     "//src/cdk/platform",
-    "//src/cdk/overlay",
+    "//src/cdk/scrolling",
     "//src/cdk/bidi",
     "//src/cdk/coercion",
   ],