siteAdmin: wait for all report data to load before rendering
Created by: bobheadxi
closes https://github.com/sourcegraph/sourcegraph/issues/11806
Suspected race condition in DynamicallyImportedMonacoSettingsEditor
has been causing alerts data to load inconsistently. This PR works around it by rendering a loader until all data is available.
Opened a separate issue re: potentially fixing the root cause: https://github.com/sourcegraph/sourcegraph/issues/11890