[BUG] Check for duplicate data source id before fetching the data sources in index pattern selector

[BionIT]

Description

This change adds check for duplicate data source id before fetching the data sources in index pattern selector

Issues Resolved

Screenshot

duplicate.mp4

Testing the changes

The following steps were performed in the recording above:

1. revert the change, go to maps plugin, and add a layer, see the bulk get payload which shows duplicate data source id
2. apply the change, go to maps plugin, and add a layer, see the bulk get payload which shows unique data source id

Changelog

• skip

Check List

• All tests pass
  • yarn test:jest
  • yarn test:jest_integration
• New functionality includes testing.
• New functionality has been documented.
• Update CHANGELOG.md
• Commits are signed per the DCO using --signoff

[ruanyl]

Approved with a minor comment

[ruanyl]

I think we can simplify the logic a bit like this, then we don't need to add an extra variable dataSourceIdSet

Suggested change

	if (
	dataSourceReference &&
	!this.state.dataSourceIdToTitle.has(dataSourceReference.id) &&
	!dataSourceIdSet.has(dataSourceReference.id)
	) {
	dataSourceIdSet.add(dataSourceReference.id);
	const dataSourcesToFetch = new Set<string>();
	savedObjects.map((indexPatternSavedObject: SimpleSavedObject<any>) => {
	const dataSourceReference = getDataSourceReference(indexPatternSavedObject.references);
	if (dataSourceReference && !this.state.dataSourceIdToTitle.has(dataSourceReference.id)) {
	dataSourcesToFetch.add(dataSourceReference.id);
	}
	});
	const dataSourceIdToTitleToUpdate = new Map();
	if (dataSourcesToFetch.size > 0) {
	const resp = await savedObjectsClient.bulkGet(
	[...dataSourcesToFetch].map((id) => ({ type: 'data-source', id }))
	);