function updateCustomerApiKeyId (cognitoIdentityId, apiKeyId, error, success) {
  console.log(`Updating API Key for identity ID [${cognitoIdentityId}]`)

  // update customer record with marketplace customer code
  const dynamoDbParams = {
    TableName: getCustomersTableName(),
    Key: {
      Id: cognitoIdentityId
    },
    UpdateExpression: 'set #a = :x',
    ExpressionAttributeNames: { '#a': 'ApiKeyId' },
    ExpressionAttributeValues: {
      ':x': apiKeyId
    }
  }

  dynamoDb.update(dynamoDbParams, dynamoDbErr => {
    if (dynamoDbErr) {
      console.error('Failed to updated API Key:', dynamoDbErr)
      error(dynamoDbErr)
    } else {
      console.log(`Updated API Key for identity ID [${cognitoIdentityId}]`)
      success()
    }
  })
}
Updates the account's `ApiKey` column in the CustomersTable.

Precondition: the corresponding CustomersTable item must already exist.