Change description of context.group action variable (#150104)

## Summary

This PR changes the description of `context.group` action variable in
Metric threshold rule and Log threshold rule. The background of this
change can be found in [this
PR](#149071 (comment)).

## Metric threshold rule
**Old description:** Name of the group reporting data
**New description:** Name of the group(s) reporting data. For accessing
each group key, use context.groupByKeys.

<img width="323" alt="Screenshot 2023-02-01 at 21 30 34"
src="https://user-images.githubusercontent.com/69037875/216156662-24e65c80-4592-4f0b-b54f-5a64d72326d2.png">

## Log threshold rule
**Old description:** The name of the group responsible for triggering
the alert
**New description:** The name of the group(s) responsible for triggering
the alert. For accessing each group key, use context.groupByKeys.

<img width="319" alt="Screenshot 2023-02-01 at 21 26 41"
src="https://user-images.githubusercontent.com/69037875/216156464-9a31f0ac-7450-435d-b56d-e72da2d82d49.png">

@maciejforcone please let me know in case the wording should be changed.

### Checklist

- [x] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)

x-pack/plugins/infra/server/lib/alerting/common/messages.ts

@@ -162,13 +162,6 @@ export const buildInvalidQueryAlertReason = (filterQueryText: string) =>
     },
   });
 
-export const groupActionVariableDescription = i18n.translate(
-  'xpack.infra.metrics.alerting.groupActionVariableDescription',
-  {
-    defaultMessage: 'Name of the group reporting data',
-  }
-);
-
 export const groupByKeysActionVariableDescription = i18n.translate(
   'xpack.infra.metrics.alerting.groupByKeysActionVariableDescription',
   {

x-pack/plugins/infra/server/lib/alerting/inventory_metric_threshold/register_inventory_metric_threshold_rule_type.ts

@@ -28,7 +28,6 @@ import {
   alertStateActionVariableDescription,
   cloudActionVariableDescription,
   containerActionVariableDescription,
-  groupActionVariableDescription,
   hostActionVariableDescription,
   labelsActionVariableDescription,
   metricActionVariableDescription,
@@ -75,6 +74,13 @@ const condition = schema.object({
   ),
 });
 
+const groupActionVariableDescription = i18n.translate(
+  'xpack.infra.inventory.alerting.groupActionVariableDescription',
+  {
+    defaultMessage: 'Name of the group reporting data',
+  }
+);
+
 export async function registerMetricInventoryThresholdRuleType(
   alertingPlugin: PluginSetupContract,
   libs: InfraBackendLibs

x-pack/plugins/infra/server/lib/alerting/log_threshold/register_log_threshold_rule_type.ts

@@ -51,7 +51,8 @@ const conditionsActionVariableDescription = i18n.translate(
 const groupByActionVariableDescription = i18n.translate(
   'xpack.infra.logs.alerting.threshold.groupByActionVariableDescription',
   {
-    defaultMessage: 'The name of the group responsible for triggering the alert',
+    defaultMessage:
+      'The name of the group(s) responsible for triggering the alert. For accessing each group key, use context.groupByKeys.',
   }
 );
 

x-pack/plugins/infra/server/lib/alerting/metric_threshold/register_metric_threshold_rule_type.ts

@@ -17,7 +17,6 @@ import {
   alertStateActionVariableDescription,
   cloudActionVariableDescription,
   containerActionVariableDescription,
-  groupActionVariableDescription,
   groupByKeysActionVariableDescription,
   hostActionVariableDescription,
   labelsActionVariableDescription,
@@ -108,6 +107,14 @@ export async function registerMetricThresholdRuleType(
     label: schema.maybe(schema.string()),
   });
 
+  const groupActionVariableDescription = i18n.translate(
+    'xpack.infra.metrics.alerting.groupActionVariableDescription',
+    {
+      defaultMessage:
+        'Name of the group(s) reporting data. For accessing each group key, use context.groupByKeys.',
+    }
+  );
+
   alertingPlugin.registerType({
     id: METRIC_THRESHOLD_ALERT_TYPE_ID,
     name: i18n.translate('xpack.infra.metrics.alertName', {