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

chrome/common/net/PRESUBMIT.py

Index: chrome/common/net/PRESUBMIT.py
diff --git a/chrome/common/net/PRESUBMIT.py b/chrome/common/net/PRESUBMIT.py
index 05acff5ced2a6362f5ef3e0c11992f5abf2f6bbd..20f41f6deba186a8f7ecac48c9dd5be7ef21884e 100644
--- a/chrome/common/net/PRESUBMIT.py
+++ b/chrome/common/net/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']),
     }
   }