[ReleasePR alertsmanagement] [Hub Generated] Public private branch 'dev-alertsmanagement-Microsoft.AlertsManagement-2021-02-01-preview' (#1894)

Create to sync Azure/azure-rest-api-specs#15899
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/main...AzureSDKAutomation:sdkAuto/alertsmanagement?expand=1)

Author: msftbot[bot]