Revert "commands:  Remove topology usage to simplify authentication"

This reverts commit 77cd8ebcfb940d0736db2ef323522c8c71285274.

Reason for revert: https://bugs.chromium.org/p/chromium/issues/detail?id=937154

Original change's description:
> commands:  Remove topology usage to simplify authentication
> 
> Topology seems to be used in a broad way, resulting in unpredictable
> behavior in older branches.  Remove the use of topology, as it provides
> little value in this context, and simplify the usage to consume constants.
> 
> BUG=chromium:931793
> TEST='cros tryjob --hwtest --staging samus-paladin-tryjob bob-paladin-tryjob'
> 
> Change-Id: I7d11e72e3489a6e0b7e55a680d2cb0401da9d3f1
> Reviewed-on: https://chromium-review.googlesource.com/c/1493100
> Reviewed-by: Jason Clinton <jclinton@chromium.org>
> Tested-by: Mike Nichols <mikenichols@chromium.org>
> Commit-Queue: Mike Nichols <mikenichols@chromium.org>

Bug: chromium:931793
Change-Id: I3841519fe83513b82376d9ebaef0dd6e09b086e8
Reviewed-on: https://chromium-review.googlesource.com/c/1495928
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
Commit-Queue: Bernie Thompson <bhthompson@chromium.org>
Tested-by: Bernie Thompson <bhthompson@chromium.org>
diff --git a/cbuildbot/commands.py b/cbuildbot/commands.py
index 7910195..8d79417 100644
--- a/cbuildbot/commands.py
+++ b/cbuildbot/commands.py
@@ -1497,7 +1497,6 @@
       'hard_timeout_secs': swarming_timeout,
       'expiration_secs': _SWARMING_EXPIRATION,
       'tags': tags,
-      'service_account_json': constants.CHROMEOS_SERVICE_ACCOUNT,
   }
 
 
diff --git a/lib/constants.py b/lib/constants.py
index 7b38747..01ef0a2 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -1262,15 +1262,3 @@
 # Mock build and stage IDs
 MOCK_STAGE_ID = 313377
 MOCK_BUILD_ID = 31337
-
-# Topology dictionary copied from CIDB.
-TOPOLOGY_DICT = {
-    '/buildbucket/host':'cr-buildbucket.appspot.com',
-    '/chrome_swarming_proxy/host':'chromeos-swarming.appspot.com',
-    '/datastore/creds_file':('/creds/service_accounts/service-account-chromeos'
-                             '-datastore-writer-prod.json'),
-    '/sheriffomatic/host':'sheriff-o-matic.appspot.com',
-    '/statsd/es_host':'104.154.79.237',
-    '/statsd/host':'104.154.79.237',
-    '/swarming_proxy/host':'chromeos-proxy.appspot.com',
-}