changefeedccl: Remove metrics scope library.

Remove metrics scope library since it has been moved under changefeedccl.

Note: this is a move only refactoring, but it is structured as 2 changes
(one to add new files, and one to remove cdcutils files) so that it can
be easily backported.

Release Notes: None

pkg/ccl/changefeedccl/cdcutils/BUILD.bazel

@@ -2,10 +2,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "cdcutils",
-    srcs = [
-        "metrics_scope.go",
-        "throttle.go",
-    ],
+    srcs = ["throttle.go"],
     importpath = "github.com/cockroachdb/cockroach/pkg/ccl/changefeedccl/cdcutils",
     visibility = ["//visibility:public"],
     deps = [
@@ -21,17 +18,13 @@ go_library(
 
 go_test(
     name = "cdcutils_test",
-    srcs = [
-        "metrics_scope_test.go",
-        "throttle_test.go",
-    ],
+    srcs = ["throttle_test.go"],
     embed = [":cdcutils"],
     deps = [
         "//pkg/ccl/changefeedccl/changefeedbase",
         "//pkg/settings/cluster",
         "//pkg/util/leaktest",
         "//pkg/util/log",
-        "//pkg/util/metric",
         "@com_github_stretchr_testify//require",
     ],
 )