Use official manifest on official builders.
Use official manifest on official builders.

Currently, the sonic builders try to build sonic.xml, but this does not
work particularly well for paladin or release builders since we have a
master/slave build system. If each slave were to need a separate
manifest we would need to sync each manifest separately and somehow keep
them in sync, which would be difficult.

Creating a single manifest to rule them all makes things easier. This
official manifest contains some repositories that only bots have access
to. We still create board-specific manifests for developers who only,
for example, have access to a single board and don't have access to the
all official board manifests.

In this change, we've switched all official builders to use official.xml,
which is a superset of all other manifests.

BUG=chromium:219692
TEST=--buildbot --debug runs, all unit tests
Change-Id: I5012dcb7fcb6cf60fd560b5275be9b94f06286ae
Reviewed-on: https://gerrit.chromium.org/gerrit/50508
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Reviewed-by: Ryan Cui <5ce1592d53754a87a44fc2eb7b63d5f77cf50fdb@chromium.org>
Tested-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Queue: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>

bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite