Config touch ups to luci-milo-dev.cfg.

These changes simplify migrating to starlark by removing spurious diffs
from the semantic diff.

The header_id fields have no effect when builder_view_only is true
because builder views do not display headers.

The manifest_name field is ignored and cannot be set in starlark.

Bug: 1011908
Change-Id: I92d1fd67ba41a68fefdc5524ee0acbc583cfc9d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1869684
Auto-Submit: Garrett Beaty <gbeaty@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707576}

infra/config/generated/luci-milo-dev.cfg

@@ -179,8 +179,6 @@ consoles {
 consoles {
   id: "snapshots"
   builder_view_only: true
-  header_id: "chromium"
-  manifest_name: "REVISION"
   name: "Snapshot Builder"
   builders {
     name: "buildbucket/luci.chromium.cron/Snapshot Builder"

infra/config/luci-milo-dev.cfg

@@ -179,8 +179,6 @@ consoles {
 consoles {
   id: "snapshots"
   builder_view_only: true
-  header_id: "chromium"
-  manifest_name: "REVISION"
   name: "Snapshot Builder"
   builders {
     name: "buildbucket/luci.chromium.cron/Snapshot Builder"