[7.x] Disable the experimental metrics_entities plugin by default. (#…

…115460) (#115694)

* Disable the experimental `metrics_entities` plugin by default. (#115460)

This was default disabled in 7.15, but we needed a code change to maintain that (consistent) behavior.
# Conflicts:
#	x-pack/plugins/metrics_entities/server/index.ts

* Remove old config for metrics

* Remove unused imports

Co-authored-by: Robert Austin <robert.austin@elastic.co>
Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/metrics_entities/server/index.ts

@@ -4,21 +4,24 @@
  * 2.0; you may not use this file except in compliance with the Elastic License
  * 2.0.
  */
+import { schema } from '@kbn/config-schema';
 
-import { PluginConfigDescriptor, PluginInitializerContext } from '../../../../src/core/server';
+import { PluginInitializerContext } from '../../../../src/core/server';
 
-import { ConfigSchema } from './config';
 import { MetricsEntitiesPlugin } from './plugin';
 
+export { MetricsEntitiesPluginSetup, MetricsEntitiesPluginStart } from './types';
+
 //  This exports static code and TypeScript types,
 //  as well as, Kibana Platform `plugin()` initializer.
 
-export const config: PluginConfigDescriptor = {
-  deprecations: ({ deprecate }) => [deprecate('enabled', '8.0.0')],
-  schema: ConfigSchema,
-};
 export const plugin = (initializerContext: PluginInitializerContext): MetricsEntitiesPlugin => {
   return new MetricsEntitiesPlugin(initializerContext);
 };
 
-export { MetricsEntitiesPluginSetup, MetricsEntitiesPluginStart } from './types';
+export const config = {
+  schema: schema.object({
+    // This plugin is experimental and should be disabled by default.
+    enabled: schema.boolean({ defaultValue: false }),
+  }),
+};