change kibana.yml xpack.actions.whitelistedHosts to default to ['*'] (#52827)

resolves https://github.com/elastic/kibana/issues/52597

The previous default was `[]`, which meant no hosts were whitelisted,
which would require a Kibana admin to set this value for any actions
that accessed 3rd party services (currently email and webhook, longer
term slack and pagerduty).

docs/setup/settings.asciidoc

@@ -390,6 +390,11 @@ Rollup user interface.
 
 `i18n.locale`:: *Default: en* Set this value to change the Kibana interface language. Valid locales are: `en`, `zh-CN`, `ja-JP`.
 
+`xpack.actions.whitelistedHosts:`:: *Default: +[ {asterisk} ]+* Set this value
+to an array of host names which actions such as email, slack, pagerduty, and
+webhook can connect to.  An element of `*` indicates any host can be connected
+to.  An empty array indicates no hosts can be connected to.
+
 
 include::{docdir}/settings/apm-settings.asciidoc[]
 include::{docdir}/settings/dev-settings.asciidoc[]

x-pack/legacy/plugins/actions/index.ts

@@ -41,7 +41,7 @@ export function actions(kibana: any) {
                 .allow('*')
             )
             .sparse(false)
-            .default([]),
+            .default(['*']),
         })
         .default();
     },

x-pack/test/alerting_api_integration/common/config.ts

@@ -53,12 +53,10 @@ export function createTestConfig(name: string, options: CreateTestConfigOptions)
         ...xPackApiIntegrationTestsConfig.get('kbnTestServer'),
         serverArgs: [
           ...xPackApiIntegrationTestsConfig.get('kbnTestServer.serverArgs'),
-          '--xpack.actions.enabled=true',
           `--xpack.actions.whitelistedHosts=${JSON.stringify([
             'localhost',
             'some.non.existent.com',
           ])}`,
-          '--xpack.alerting.enabled=true',
           ...disabledPlugins.map(key => `--xpack.${key}.enabled=false`),
           `--plugin-path=${path.join(__dirname, 'fixtures', 'plugins', 'alerts')}`,
           `--plugin-path=${path.join(__dirname, 'fixtures', 'plugins', 'actions')}`,