[Logs+] Improve observability log explorer global search behaviour (#167164)

## Summary

- Closes https://github.com/elastic/kibana/issues/166854 by disabling
the Observability Log Explorer plugin in the es and security serverless
projects.

- Closes https://github.com/elastic/kibana/issues/166912 by expanding
results with `keywords`.

---------

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

config/serverless.es.yml

@@ -5,6 +5,7 @@ xpack.apm.enabled: false
 
 xpack.cloudSecurityPosture.enabled: false
 xpack.infra.enabled: false
+xpack.observabilityLogExplorer.enabled: false
 xpack.observability.enabled: false
 xpack.securitySolution.enabled: false
 xpack.serverless.observability.enabled: false

config/serverless.security.yml

@@ -4,6 +4,7 @@
 enterpriseSearch.enabled: false
 xpack.apm.enabled: false
 xpack.infra.enabled: false
+xpack.observabilityLogExplorer.enabled: false
 xpack.observability.enabled: false
 xpack.uptime.enabled: false
 xpack.legacy_uptime.enabled: false

x-pack/plugins/observability_log_explorer/public/plugin.ts

@@ -55,6 +55,7 @@ export class ObservabilityLogExplorerPlugin
         ? AppNavLinkStatus.visible
         : AppNavLinkStatus.hidden,
       searchable: true,
+      keywords: ['logs', 'log', 'explorer', 'logs explorer'],
       mount: async (appMountParams) => {
         const [coreStart, pluginsStart, ownPluginStart] = await core.getStartServices();
 

x-pack/plugins/observability_log_explorer/server/config.ts

@@ -10,6 +10,7 @@ import { PluginConfigDescriptor } from '@kbn/core/server';
 import { ObservabilityLogExplorerConfig } from '../common/plugin_config';
 
 export const configSchema = schema.object({
+  enabled: schema.boolean({ defaultValue: true }),
   navigation: schema.object({
     showAppLink: offeringBasedSchema({
       serverless: schema.boolean({