Moving Priority and EvictionPolicy enum to the definitions section and adding 'Spot' priority. Updating both 2019-03-01 and 2019-07-01 Api versions.

[rakeshakkera]

Latest improvements:

MSFT employees can try out our new experience at OpenAPI Hub - one location for using our validation tools and finding your workflow.

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• I have reviewed the documentation for the workflow.
• Validation tools were run on swagger spec(s) and have all been fixed in this PR.
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• adding/removing APIs.
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[AutorestCI]

Automation for azure-sdk-for-python

The initial PR has been merged into your service PR:
Azure/azure-sdk-for-python#8464

[azuresdkci]

Can one of the admins verify this patch?

[AutorestCI]

Automation for azure-sdk-for-go

The initial PR has been merged into your service PR:
Azure/azure-sdk-for-go#6312