[ledger auth] Add new metric for ledger firebase auth errors.

Ledger authentication is moving to a new auth service provided at
//garnet/public/fidl/fuchsia.auth/token_manager.fidl

As a result, the error codes are different. During the migration and
rollback, both metrics are used and could overlap. So, to keep the
error buckets separate for each flow, creating a new metric id 4. Once
the new flow is in full use, we will get rid of the old metric id 3.

TEST = CQ

Change-Id: I1d2493bb1b70a0889b118726aaf625fb87812501
1 file changed