The FlagGrafanaAPIServerWithExperimentalAPIs is only available when
`app_mode=development`. We have a more specific flag that is usable in
production, so use that.
Also, there was some old code constraining these APIs to a static list
of datasources. We don't need that anymore, so this PR removes it.
The FlagQueryServiceWithConnections is left as is, because there are
multiple existing tests that rely on this development-only, experimental
flag. I don't want to understand why that is.
beejeebus
6d64c373ce