[Backport 2.x] Data sources bug fixes and UI improvements #1552

Job	Run time
Run test group of app_analytics_test	19m 36s
Run test group of datasources_test	11m 17s
Run test group of event_analytics_test	22m 23s
Run test group of integrations_test	11m 25s
Run test group of metrics_analytics_test	12m 1s
Run test group of notebooks_test	14m 44s
Run test group of panels_test	14m 44s
Run test group of trace_analytics_test	29m 28s
	2h 15m 38s

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