trait CustomerTrait {
	/**
     * @ORM\Column(name="customer_type", type="string", length=255, nullable=true)
     * @Eccube\FormAppend(
     *  auto_render=true,
     *  type="\Symfony\Component\Form\Extension\Core\Type\ChoiceType",
     *  options={
     *    "required": true,
     *    "label": "会員種類",
     *  }
     * )
     */
    private $customer_type;

    public function getcustomertype() {
        return $this->customer_type;
    }

    public function setcustomertype($customer_type) {
        $this->customer_type = $customer_type;

        return $this;
    }

    (最初に追加した項目…中略)

}

->add('job', JobType::class, [
    'required' => false,
])        // ";"を削除
->add('customer_type', ChoiceType::class, [
    'required' => true,
    'expanded' => true,
    'multiple' => false,
    'choices'  => [
        '一般会員'   => 'normal',
        'プレミアム会員' => 'premium',
    ],
]);

use Symfony\Component\Form\Extension\Core\Type\ChoiceType;