Replace injected vars with exposeToBrowser

[flash1293]

Kibana app code uses injected vars in several places. As described in #54376 all usages should be replaced by exposeToBrowser:

Done	Injected Var	Source	Usage	Action Plan	PR
✅	kbnDefaultAppId	config key kibana.defaultAppId	several places in kibana plugin, discover, dashboard_mode	Move into kibana_legacy plugin and expose via contract	#55937
✅	disableWelcomeScreen	config key kibana.disableWelcomeScreen	home	Move into home plugin, change to home.disableWelcomeScreen and map kibana.disableWelcomeScreen over with a deprecation warning (see src/core/server/config/deprecation/types.ts)	#55937
-	autocompleteTerminateAfter	config key kibana.autocompleteTerminateAfter	input control vis	leave as is for now, will be handled by app arch
-	autocompleteTimeout	config key kibana.autocompleteTimeout	input control vis	leave as is for now, will be handled by app arch
✅	timelionUiEnabled	config key timelion.ui.enabled	timelion	Move into timelion and expose via contract
-	emsTileLayerId	-	vega	leave as is for now, will be handled by Maps
✅	enableExternalUrls	config key vega.enableExternalUrls	vega	Create vega NP plugin, expose via contract
✅	telemetryEnabled	config key telemetry.enabled	home	leave as is for now, will be handled by Pulse
✅	telemetryBanner	config key telemetry.allowChangingOptInStatus	home	leave as is for now, will be handled by Pulse
-	esShardTimeout	esConfig.shardTimeout,(src/legacy/core_plugins/elasticsearch/index.js)- exposed by es plugin?	vega	leave as is for now, will be handled by platform
✅	graphSavePolicy	config key xpack.graph.savePolicy	graph	move into graph and expose via contract
✅	canEditDrillDownUrls	config key xpack.graph.canEditDrillDownUrls	graph	move into graph and expose via contract

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[flash1293]

@ppisljar @Bargs The settings for autocompleteTerminateAfter and autocompleteTimeout are used for the suggestions in the search bar and for the input control vis. I'm not sure where they belong long-term. Should we move them to the data plugin (data.autocompleteTerminateAfter)? I'm also fine with splitting them up into inputControl.autocompleteTerminateAfter and data.autocompleteTerminateAfter.

Edit: Scratch that - just saw #46705 (comment)

[flash1293]

Closing this as all config keys managed by the Kibana app team are migrated, the rest will be handled by the respective owners