Revert "cbuildbot: split debug symbols into a dedicated stage"

This reverts CL:176249, which we suspect causes hangs in
cbuildbot_stages_unittest.

BUG=chromium:319583
TEST=Run it and verify that unittests still pass.

Change-Id: I814c962d413164bd206794a47f3ce8e6dfdc3e20
Reviewed-on: https://chromium-review.googlesource.com/176892
Commit-Queue: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index 89d41cc..8c3d7f9 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -429,11 +429,6 @@
       self._RunStage(stages.UnitTestStage, board, config=config)
       return
 
-    # While this stage list is run in parallel, the order here dictates the
-    # order that things will be shown in the log.  So group things together
-    # that make sense when read in order.  Also keep in mind that, since we
-    # gather output manually, early slow stages will prevent any output from
-    # later stages showing up until it finishes.
     stage_list = []
     if self.options.chrome_sdk and self.build_config['chrome_sdk']:
       stage_list.append([stages.ChromeSDKStage, board, archive_stage])
@@ -442,8 +437,7 @@
         [stages.SignerTestStage, board, archive_stage],
         [stages.UnitTestStage, board],
         [stages.UploadPrebuiltsStage, board, archive_stage],
-        [stages.DevInstallerPrebuiltsStage, board, archive_stage],
-        [stages.DebugSymbolsStage, board, archive_stage],
+        [stages.DevInstallerPrebuiltsStage, board, archive_stage]
     ]
 
     # We can not run hw tests without archiving the payloads.