Remove unused graph targets (#4990)

Author: gchatelet

ortools/base/BUILD.bazel

@@ -548,12 +548,6 @@ cc_library(
     ],
 )
 
-cc_library(
-    name = "top_n",
-    hdrs = ["top_n.h"],
-    deps = [":logging"],
-)
-
 cc_library(
     name = "types",
     hdrs = ["types.h"],