UI: Please change memory setting in flex compute offering from MiB to GiB

### The required feature described as a wish

As a user, I'd like to be able to set the memory size of my instances in GiB without having to calculate the correct MiB value.
Entering values in MiB tends to lead to entering round numbers of 1,000. This then results in odd GiB values.
If a VM with less than 1 GiB is ever actually needed, you can enter 0.5 GiB, for example.
However, this use case is likely to occur much less frequently than higher GiB values.

Maybe it could include a drop-down menu next to the value that uses GiB as the default but also allows MiB to be selected. But I think GiB is the most helpful for most people.

首先定位 flex compute 产品的 UI 以及当前接受 MiB 值的内存字段，然后检查附近的 UI 测试。完成的标准是用户默认可以以 GiB 输入内存，包括 0.5 这样的分数值；如果现有设计支持单位选择器，还应提供所要求的 MiB 选项。

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