Stop using/throwing boom errors in the NP elasticsearch service

[pgayvallet]

ATM, any error thrown by the ES client/service is a wrapped boom error

kibana/src/core/server/elasticsearch/errors.ts

Lines 30 to 32 in 01ac90f

	export interface ElasticsearchError extends Boom {
	[code]?: string;
	}

This made sense in the legacy platform, however in NP we are discouraging usage of boom errors in favor of manual error handling (mostly in the route handlers). We should return non-boom, specialised errors instead.

[elasticmachine]

Pinging @elastic/kibana-platform (Team:Platform)

[joshdover]

Given that we're doing #35508, is this worth doing at all or should we just wait until we remove it?

[pgayvallet]

I think we should just wait until the removal of the legacy ES client 'resolves' this issue.

[rudolf]

This has been fixed 🥳 (probably as part of #35508)