Add infra_tests.py, recipe, buildbotless bot

Have the presubmit (upload) run infra_tests.py if anything in infra/ changed.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2415193002

Review-Url: https://codereview.chromium.org/2415193002
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index f0b5f42..a6d1d16 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -167,32 +167,14 @@
   return results
 
 
-def _RecipeSimulationTest(input_api, output_api):
-  """Run the recipe simulation test."""
+def _InfraTests(input_api, output_api):
+  """Run the infra tests."""
   results = []
   if not any(f.LocalPath().startswith('infra')
              for f in input_api.AffectedFiles()):
     return results
 
-  recipes_py = os.path.join('infra', 'bots', 'recipes.py')
-  cmd = ['python', recipes_py, 'simulation_test']
-  try:
-    subprocess.check_output(cmd)
-  except subprocess.CalledProcessError as e:
-    results.append(output_api.PresubmitError(
-        '`%s` failed:\n%s' % (' '.join(cmd), e.output)))
-  return results
-
-
-def _GenTasksTest(input_api, output_api):
-  """Run gen_tasks.go test."""
-  results = []
-  if not any(f.LocalPath().startswith('infra')
-             for f in input_api.AffectedFiles()):
-    return results
-
-  gen_tasks = os.path.join('infra', 'bots', 'gen_tasks.go')
-  cmd = ['go', 'run', gen_tasks, '--test']
+  cmd = ['python', os.path.join('infra', 'bots', 'infra_tests.py')]
   try:
     subprocess.check_output(cmd)
   except subprocess.CalledProcessError as e:
@@ -254,8 +236,7 @@
   results.extend(_CommonChecks(input_api, output_api))
   # Run on upload, not commit, since the presubmit bot apparently doesn't have
   # coverage or Go installed.
-  results.extend(_RecipeSimulationTest(input_api, output_api))
-  results.extend(_GenTasksTest(input_api, output_api))
+  results.extend(_InfraTests(input_api, output_api))
 
   results.extend(_CheckGNFormatted(input_api, output_api))
   return results