[Telemetry] Revert increment of json test list version.

This broke the android scripts.

BUG=388885
TBR=dtu@chromium.org
NOTRY=True

Review URL: https://codereview.chromium.org/599743002

Cr-Commit-Position: refs/heads/master@{#296324}

tools/telemetry/telemetry/test_runner.py

@@ -271,7 +271,7 @@ def _GetJsonTestList(possible_browser, has_reference, test_classes, num_shards):
   }
   """
   output = {
-    'version': 2,
+    'version': 1,
     'steps': {
     }
   }