insights: insights returned from graphQL don't respect soft delete

Created by: coury-clark

The underlying table insight_series has a soft delete column deleted_at. The method GetMapped in the InsightStore doesn't respect this soft delete, and will return 'deleted' insights by default.

https://sourcegraph.com/-/editor?remote_url=git%40github.com%3Asourcegraph%2Fsourcegraph.git&branch=main&file=enterprise%2Finternal%2Finsights%2Fstore%2Finsight_store.go&editor=JetBrains&version=v1.2.1&utm_product_name=GoLand&utm_product_version=2021.1.3&start_row=75&start_col=26&end_row=75&end_col=26