Convert manually triggered try runs to use bots without _swarming prefix.

chrome/browser/sync/PRESUBMIT.py

Index: chrome/browser/sync/PRESUBMIT.py
diff --git a/chrome/browser/sync/PRESUBMIT.py b/chrome/browser/sync/PRESUBMIT.py
index b3bcb5f737995d0ef513e37d230716a768828bf5..84200943f08ffbfa6d9bb42061477704ae886521 100644
--- a/chrome/browser/sync/PRESUBMIT.py
+++ b/chrome/browser/sync/PRESUBMIT.py
@@ -11,12 +11,12 @@ for more details on the presubmit API built into gcl.
 def GetPreferredTryMasters(project, change):
   return {
     'tryserver.chromium.linux': {
-      'linux_chromium_rel_swarming': set(['defaulttests']),
+      'linux_chromium_rel': set(['defaulttests']),
     },
     'tryserver.chromium.mac': {
-      'mac_chromium_rel_swarming': set(['defaulttests']),
+      'mac_chromium_rel': set(['defaulttests']),
     },
     'tryserver.chromium.win': {
-      'win_chromium_rel_swarming': set(['defaulttests']),
+      'win_chromium_rel': set(['defaulttests']),
     }
   }