configs: remove euleros_defconfig

euleros inclusion
category: bugfix
bugzilla: 46918

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EulerOS is compatible with openEuler KABI, use the same config;
So arch/arm64/configs/euleros_defconfig file is no longer used;
Signed-off-by: Nzhoukang <zhoukang7@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>