Tidy up test matrix of test_scanner.py

class TestScannersAllTableFormats(ImpalaTestSuite):
  BATCH_SIZES = [0, 1, 16]

  @classmethod
  def get_workload(cls):
    return 'functional-query'

  @classmethod
  def add_test_dimensions(cls):
    super(TestScannersAllTableFormats, cls).add_test_dimensions()
    if cls.exploration_strategy() == 'core':
      # The purpose of this test is to get some base coverage of all the file formats.
      # Even in 'core', we'll test each format by using the pairwise strategy.
      cls.ImpalaTestMatrix.add_dimension(cls.create_table_info_dimension('pairwise'))
    cls.ImpalaTestMatrix.add_dimension(
        ImpalaTestDimension('batch_size', *TestScannersAllTableFormats.BATCH_SIZES))
    cls.ImpalaTestMatrix.add_dimension(
        ImpalaTestDimension('debug_action', *DEBUG_ACTION_DIMS))
    cls.ImpalaTestMatrix.add_dimension(ImpalaTestDimension('mt_dop', *MT_DOP_VALUES))

  def test_scanners(self, vector):
    new_vector = deepcopy(vector)
    # Copy over test dimensions to the matching query options.
    new_vector.get_value('exec_option')['batch_size'] = vector.get_value('batch_size')
    new_vector.get_value('exec_option')['debug_action'] = vector.get_value('debug_action')
    new_vector.get_value('exec_option')['mt_dop'] = vector.get_value('mt_dop')
    self.run_test_case('QueryTest/scanners', new_vector)

  def test_many_nulls(self, vector):
    if vector.get_value('table_format').file_format == 'hbase':
      # manynulls table not loaded for HBase
      pytest.skip()
    # Copy over test dimensions to the matching query options.
    new_vector = deepcopy(vector)
    new_vector.get_value('exec_option')['batch_size'] = vector.get_value('batch_size')
    new_vector.get_value('exec_option')['debug_action'] = vector.get_value('debug_action')
    new_vector.get_value('exec_option')['mt_dop'] = vector.get_value('mt_dop')
    self.run_test_case('QueryTest/scanners-many-nulls', new_vector)

  def test_hdfs_scanner_profile(self, vector):
    if vector.get_value('table_format').file_format in ('kudu', 'hbase') or \
       vector.get_value('exec_option')['num_nodes'] != 0:
      pytest.skip()
    self.run_test_case('QueryTest/hdfs_scanner_profile', vector)

  def test_string_escaping(self, vector):
    """Test handling of string escape sequences."""
    if vector.get_value('table_format').file_format == 'rc':
      # IMPALA-7778: RCFile scanner incorrectly ignores escapes for now.
      self.run_test_case('QueryTest/string-escaping-rcfile-bug', vector)
    else:
      self.run_test_case('QueryTest/string-escaping', vector)