Use getDefaultQuery method to set default query

[sunker]

Instead of calling onChange to set default query for new queries, we should use the new getDefaultQuery method defined in the data source api. We can use the same default query as today.

redshift-datasource/src/types.ts

Lines 40 to 44 in bbfb1e8

	export const defaultQuery: Partial<RedshiftQuery> = {
	rawSQL: '',
	format: FormatOptions.TimeSeries,
	fillMode: { mode: FillValueOptions.Previous },
	};

Part of https://github.com/grafana/cloud-data-sources/issues/79

[idastambuk]

Closing as "won't do"
See https://github.com/grafana/oss-plugin-partnerships/issues/79#issuecomment-1549740717 for info