The Security plugin should not rely on _cat APIs

[jportner]

The _cat APIs are only intended for humans, not machine consumption, and they are subject to change without warning.

The Security plugin's security_checkup module currently relies on cat.indices to check and see if there is any user data:

kibana/x-pack/plugins/security/server/security_checkup/check_cluster_data.ts

Lines 16 to 25 in 64f37e7

	const indices = await esClient.cat.indices({
	format: 'json',
	h: ['index', 'docs.count'],
	});
	clusterHasUserData = indices.body.some((indexCount) => {
	const isInternalIndex =
	indexCount.index?.startsWith('.') || indexCount.index?.startsWith('kibana_sample_');
	return !isInternalIndex && parseInt(indexCount['docs.count']!, 10) > 0;
	});

We should change to use indices.stats instead.

[elasticmachine]

Pinging @elastic/kibana-security (Team:Security)