[buganizer] Migrate DIR_METADATA for dbus/

Migrate all metadata files for dbus/ and mixins
used by metadata files under dbus/.

Verify components with http://b/components/{id} or at
go/chrome-on-buganizer-prod-components.

Bug: chromium:1518875
Change-Id: I8dfec877e53f31b4fbd1a2bbf8b642372a65bb15
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5235433
Reviewed-by: Ryo Hashimoto <[email protected]>
Commit-Queue: Jeff Yoon <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1252146}

Author: Jeff Yoon

dbus/COMMON_METADATA

@@ -1,3 +1,6 @@
-monorail {
+monorail: {
   component: "OS>Systems"
-}
+}
+buganizer_public: {
+  component_id: 1457034
+}