[dirmd] Deduplicate directory metadata

Programmatically delete redundant metadata.
This CL is entirely machine-generated:
1. Export the metadata in the "original" and "reduced" forms:
   dirmd read -form original > ~/tmp/dirmd/original.json
   dirmd read -form reduced  > ~/tmp/dirmd/reduced.json
2. Run reduce.py
   Source code: https://gist.github.com/nodirg/a4803af94ffe258ba0a6e0a4807141d8

The script diffs the two JSON files and strips redundant
lines from DIR_METADATA files. If the file became empty, then
removes the file.

The results of the script was verified by diffing canonical
representation of `dirmd read -form full` before and after
the script: there is no diff.

Bug: 1179786
Change-Id: Ie5de3ba0962d266244ffb9b07c874b3dbbb69b9c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2795985
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Fred Mello <fredmello@chromium.org>
Owners-Override: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Nodir Turakulov <nodir@chromium.org>
Cr-Commit-Position: refs/heads/master@{#883868}
GitOrigin-RevId: 6dfb6d1accb0d5b62ac31eac2ae080f10d64ab57
diff --git a/public/proto/DIR_METADATA b/public/proto/DIR_METADATA
deleted file mode 100644
index c5f6b73..0000000
--- a/public/proto/DIR_METADATA
+++ /dev/null
@@ -1,5 +0,0 @@
-monorail {
-  component: "Services>Safebrowsing>ChromeCleanup"
-team_email: "security-dev@chromium.org"