Add Global Setting for Start Instance Default

Add Global Setting for Start Instance Default

##### ISSUE TYPE

* Enhancement Request

##### COMPONENT NAME

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UI
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##### CLOUDSTACK VERSION

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4.19.1.1
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##### CONFIGURATION

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N/A
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##### OS / ENVIRONMENT

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KVM
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##### SUMMARY

We would like to change the default behavior at instance creation for some use cases we have. This Enhancement would add the ability to change that behavior if someone wanted to. A global setting would accomplish this and let the default out of the box still be Start by default.

##### STEPS TO REPRODUCE

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N/A - Workflow Enhancement
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##### EXPECTED RESULTS

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Global Setting that would change the default behavior of Start Instance from `Yes` to `No`. The Global setting would be set to `Yes` by default.
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##### ACTUAL RESULTS

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Default is hard coded to Start Instance at instance creation.
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首先定位实例创建路径和现有的全局设置定义；issue 未指定具体的文件或测试。完成的标准是：某个全局设置默认为 Yes，允许将 Start Instance 的默认行为改为 No，并且在不做更改时保持当前的开箱即用行为。

由索引模型根据 Issue 内容生成。