[ReleasePR timeseriesinsights] Time Series Insights - add 2021-06-30-preview API version, and supportsCustomerManagedKey output property (#1811)

Create to sync Azure/azure-rest-api-specs#15274
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/master...AzureSDKAutomation:sdkAuto/timeseriesinsights?expand=1)

Author: msftbot[bot]