fix: [Platform:StackManagement:SnapshotAndRestore:Add repository page]Missing error warning announcement (#220633)

Closes: #219355
Closes: #219345


## Summary

This PR improves accessibility for users relying on assistive
technologies for: `Analytics → Stack Management → Snapshot and Restore`
by addressing the following:

1. Screen Reader Announcements for Error Warnings
2. Duplication of announcement

Author: alexwizp

src/platform/plugins/shared/es_ui_shared/__packages_do_not_import__/authorization/components/section_error.tsx

@@ -30,7 +30,7 @@ export const SectionError: React.FunctionComponent<Props> = ({
   } = error;
 
   return (
-    <EuiCallOut title={title} color="danger" iconType="warning" {...rest}>
+    <EuiCallOut title={title} role="alert" color="danger" iconType="warning" {...rest}>
       {cause ? message || errorString : <p>{message || errorString}</p>}
       {cause && (
         <Fragment>

x-pack/platform/plugins/private/snapshot_restore/public/application/components/policy_form/steps/step_logistics.tsx

@@ -529,6 +529,7 @@ export const PolicyStepLogistics: React.FunctionComponent<StepProps> = ({
                 defaultMessage="Repository not found"
               />
             }
+            role="alert"
             color="danger"
             iconType="warning"
           >

x-pack/platform/plugins/private/snapshot_restore/public/application/components/repository_form/step_one.tsx

@@ -352,6 +352,7 @@ export const RepositoryFormStepOne: React.FunctionComponent<Props> = ({
               defaultMessage="Fix errors before continuing."
             />
           }
+          role="alert"
           color="danger"
           data-test-subj="repositoryFormError"
         />

x-pack/platform/plugins/private/snapshot_restore/public/application/components/repository_form/step_two.tsx

@@ -171,6 +171,7 @@ export const RepositoryFormStepTwo: React.FunctionComponent<Props> = ({
               defaultMessage="Fix errors before continuing."
             />
           }
+          role="alert"
           color="danger"
           iconType="cross"
           data-test-subj="repositoryFormError"

x-pack/platform/plugins/private/snapshot_restore/public/application/components/retention_update_modal_provider.tsx

@@ -21,6 +21,7 @@ import {
   EuiSpacer,
   EuiText,
   EuiCallOut,
+  useGeneratedHtmlId,
 } from '@elastic/eui';
 
 import { useCore, useServices, useToastNotifications } from '../app_context';
@@ -45,6 +46,7 @@ export const RetentionSettingsUpdateModalProvider: React.FunctionComponent<Props
   const { i18n } = useServices();
   const { docLinks } = useCore();
   const toastNotifications = useToastNotifications();
+  const modalTitleId = useGeneratedHtmlId();
 
   const [retentionSchedule, setRetentionSchedule] = useState<string>(DEFAULT_RETENTION_SCHEDULE);
   const [isModalOpen, setIsModalOpen] = useState<boolean>(false);
@@ -128,9 +130,9 @@ export const RetentionSettingsUpdateModalProvider: React.FunctionComponent<Props
     }
 
     return (
-      <EuiModal onClose={closeModal}>
+      <EuiModal onClose={closeModal} aria-labelledby={modalTitleId}>
         <EuiModalHeader>
-          <EuiModalHeaderTitle>
+          <EuiModalHeaderTitle id={modalTitleId}>
             {isEditing ? (
               <FormattedMessage
                 id="xpack.snapshotRestore.policyForm.stepRetention.policyUpdateRetentionEditTitle"
@@ -155,6 +157,7 @@ export const RetentionSettingsUpdateModalProvider: React.FunctionComponent<Props
                     defaultMessage="Error saving retention schedule"
                   />
                 }
+                role="alert"
                 color="danger"
                 iconType="warning"
               >

x-pack/platform/plugins/private/snapshot_restore/public/application/sections/home/policy_list/policy_retention_schedule/policy_retention_schedule.tsx

@@ -79,6 +79,7 @@ export const PolicyRetentionSchedule: React.FunctionComponent<Props> = ({
                             defaultMessage="Run retention now"
                           />
                         }
+                        disableScreenReaderOutput
                       >
                         <EuiButtonIcon
                           iconType="play"
@@ -108,6 +109,7 @@ export const PolicyRetentionSchedule: React.FunctionComponent<Props> = ({
                             defaultMessage="Edit retention schedule"
                           />
                         }
+                        disableScreenReaderOutput
                       >
                         <EuiButtonIcon
                           iconType="pencil"
@@ -254,6 +256,7 @@ export const PolicyRetentionSchedule: React.FunctionComponent<Props> = ({
               defaultMessage="Error fetching retention schedule"
             />
           }
+          role="alert"
           color="danger"
           iconType="warning"
         >

x-pack/platform/plugins/private/snapshot_restore/public/application/sections/home/snapshot_list/components/snapshot_search_bar.tsx

@@ -169,6 +169,7 @@ export const SnapshotSearchBar: React.FunctionComponent<Props> = ({
           <EuiCallOut
             data-test-subj="snapshotListSearchError"
             iconType="warning"
+            role="alert"
             color="danger"
             title={
               <FormattedMessage