REVERT ME: Allow multiple pruning tasks at once

Do this to get corpuses under control again.

Author: jonathanmetzman

src/clusterfuzz/_internal/bot/tasks/utasks/corpus_pruning_task.py

@@ -1114,12 +1114,13 @@ def utask_preprocess(fuzzer_name, job_type, uworker_env):
       last_execution_metadata and
       last_execution_metadata.status == data_types.TaskState.FINISHED)
 
+  # TODO: Revert me.
   # Make sure we're the only instance running for the given fuzzer and
   # job_type.
-  if not data_handler.update_task_status(task_name,
-                                         data_types.TaskState.STARTED):
-    logs.info('A previous corpus pruning task is still running, exiting.')
-    return None
+  #if not data_handler.update_task_status(task_name,
+  #                                       data_types.TaskState.STARTED):
+  #  logs.info('A previous corpus pruning task is still running, exiting.')
+  #  return None
 
   setup_input = (
       setup.preprocess_update_fuzzer_and_data_bundles(fuzz_target.engine))