Handle insufficient privileges in progression task

[jonathanmetzman]

during handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/mnt/scratch0/clusterfuzz/src/python/bot/startup/run_bot.py", line 128, in task_loop
    sys.exit(utasks.uworker_bot_main())
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/bot/tasks/utasks/__init__.py", line 220, in uworker_bot_main
    uworker_main(input_download_url)
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/bot/tasks/utasks/__init__.py", line 202, in uworker_main
    uworker_output = utask_module.utask_main(uworker_input)
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/bot/tasks/utasks/progression_task.py", line 676, in utask_main
    return find_fixed_range(uworker_input)
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/bot/tasks/utasks/progression_task.py", line 551, in find_fixed_range
    update_metadata=True)
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/bot/tasks/utasks/progression_task.py", line 361, in _testcase_reproduces_in_revision
    issue_metadata = _get_and_update_issue_metadata(testcase)
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/bot/tasks/utasks/progression_task.py", line 313, in _get_and_update_issue_metadata
    metadata = engine_common.get_all_issue_metadata_for_testcase(testcase)
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/bot/fuzzers/engine_common.py", line 460, in get_all_issue_metadata_for_testcase
    fuzz_target = testcase.get_fuzz_target()
  File "/mnt/scratch0/clusterfuzz/src/clusterfuzz/_internal/datastore/data_types.py", line 727, in get_fuzz_target
    target = ndb.Key(FuzzTarget, name).get()
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/_options.py", line 89, in wrapper
    return wrapped(*pass_args, **kwargs)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/utils.py", line 110, in positional_wrapper
    return wrapped(*args, **kwds)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/key.py", line 827, in get
    return self.get_async(_options=_options).result()
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/tasklets.py", line 193, in result
    self.check_success()
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/tasklets.py", line 140, in check_success
    raise self._exception
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/tasklets.py", line 312, in _advance_tasklet
    self.generator.throw(type(error), error, traceback)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/key.py", line 912, in get
    entity_pb = yield _datastore_api.lookup(self._key, _options)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/tasklets.py", line 312, in _advance_tasklet
    self.generator.throw(type(error), error, traceback)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/_datastore_api.py", line 156, in lookup
    entity_pb = yield batch.add(key)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/tasklets.py", line 312, in _advance_tasklet
    self.generator.throw(type(error), error, traceback)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/_retry.py", line 77, in retry_wrapper
    raise error
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/_retry.py", line 72, in retry_wrapper
    result = yield result
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/tasklets.py", line 312, in _advance_tasklet
    self.generator.throw(type(error), error, traceback)
  File "/mnt/scratch0/clusterfuzz/src/third_party/google/cloud/ndb/_datastore_api.py", line 97, in rpc_call
    raise error
google.api_core.exceptions.PermissionDenied: 403 Missing or insufficient permissions.