Remove Space Selector from Serverless Top Navigation

[sixstringcode]

For Serverless projects, there will be only a single default space, with no way to create/select additional spaces. We should remove the space icon from the top navigation for serverless projects only.

[elasticmachine]

Pinging @elastic/appex-sharedux (Team:SharedUX)

[Dosant]

It looks like this is configured purely by spaces code here:

kibana/x-pack/plugins/spaces/public/plugin.tsx

Line 99 in 0f6eca7

initSpacesNavControl(this.spacesManager, core);

@elastic/kibana-security, I think it would make more sense for you to pick this up, as you'll know better how do you want to structure this in your code. Maybe a kibana.yml which would hide space-related controls (not sure if there are others), similar to this one:

kibana/x-pack/plugins/spaces/server/config.ts

Lines 29 to 43 in 6b02be4

	allowFeatureVisibility: schema.conditional(
	schema.contextRef('serverless'),
	true,
	schema.literal(false),
	schema.boolean({
	validate: (rawValue) => {
	// This setting should not be configurable on-prem to avoid bugs when e.g. existing spaces
	// have feature visibility customized but admins would be unable to change them back if the
	// UI/APIs are disabled.
	if (rawValue === false) {
	return 'Feature visibility can only be disabled on serverless';
	}
	},
	defaultValue: true,
	})

Or maybe you have plans to disable spaces altogether in serverless?