[Discover] Replace deprecated page components (#162836)

- Closes https://github.com/elastic/kibana/issues/161426

## Summary

This PR updates usage of Eui page components for the following plugins.
Also took this opportunity to make these pages a little nicer.

### src/plugins/data_view_management

Before:
<img width="600" alt="Screenshot 2023-07-31 at 20 09 28"
src="5b52d31d-b759-40f9-8a8e-d428f6431f45">

After:
<img width="600" alt="Screenshot 2023-07-31 at 20 09 37"
src="dfd738d9-fa19-41d2-a55e-6157d9f2310a">


### examples/search_examples

Before:
<img width="600" alt="Screenshot 2023-07-31 at 17 41 03"
src="cc739f2d-bbaa-4cae-80d8-27599170a40a">

After:
<img width="600" alt="Screenshot 2023-07-31 at 18 01 47"
src="ab596aae-f9b4-48f0-8401-a507f4814624">

Before:
<img width="600" alt="Screenshot 2023-07-31 at 20 30 19"
src="40327fdd-7161-4d65-86ff-ff38455477fb">

After:
<img width="600" alt="Screenshot 2023-07-31 at 20 30 39"
src="8455c09f-6d84-4ad1-9e25-f8555a4f40db">

Before:
<img width="600" alt="Screenshot 2023-07-31 at 18 20 47"
src="68b05f4a-fcc0-4051-92b4-88a34bd22fb6">

After:
<img width="600" alt="Screenshot 2023-07-31 at 18 44 32"
src="1fd00e7e-3663-470f-927a-b7d7a0fe6c20">

### examples/partial_results_example

Before:
<img width="600" alt="Screenshot 2023-07-31 at 17 29 32"
src="589a2d93-c42a-4948-b805-0447e96f8ae4">

After:
<img width="600" alt="Screenshot 2023-07-31 at 17 31 52"
src="22df2b40-a9ec-4e11-b4dc-19da86c73059">

### examples/field_formats_example

Before:
<img width="600" alt="Screenshot 2023-07-31 at 17 27 44"
src="d3fa1fc3-e3e2-4f69-87e5-7187f8d3b000">

After:
<img width="600" alt="Screenshot 2023-07-31 at 17 27 56"
src="5633dba4-85ed-4767-bc8c-dee0c4da8798">

### examples/data_view_field_editor_example

Before:
<img width="600" alt="Screenshot 2023-07-31 at 17 33 15"
src="0be36a57-aef3-4679-ac77-9d5073b72fc2">

After:
<img width="600" alt="Screenshot 2023-07-31 at 17 37 34"
src="e43b0a1d-12fe-4d06-90b0-63cbc36e5ac2">


### Checklist

- [x] This renders correctly on smaller devices using a responsive
layout. (You can test this [in your
browser](https://www.browserstack.com/guide/responsive-testing-on-local-server))
- [x] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)

examples/partial_results_example/public/app/app.tsx

@@ -12,15 +12,9 @@ import {
   EuiBasicTable,
   EuiCallOut,
   EuiCodeBlock,
-  EuiPage,
-  EuiPageBody,
-  EuiPageContent_Deprecated as EuiPageContent,
-  EuiPageContentBody_Deprecated as EuiPageContentBody,
-  EuiPageHeader,
-  EuiPageHeaderSection,
+  EuiPageTemplate,
   EuiSpacer,
   EuiText,
-  EuiTitle,
 } from '@elastic/eui';
 import type { Datatable } from '@kbn/expressions-plugin/common';
 import { ExpressionsContext } from './expressions_context';
@@ -46,45 +40,35 @@ export function App() {
   }, [expressions]);
 
   return (
-    <EuiPage>
-      <EuiPageBody style={{ maxWidth: 1200, margin: '0 auto' }}>
-        <EuiPageHeader>
-          <EuiPageHeaderSection>
-            <EuiTitle size="l">
-              <h1>Partial Results Demo</h1>
-            </EuiTitle>
-          </EuiPageHeaderSection>
-        </EuiPageHeader>
-        <EuiPageContent>
-          <EuiPageContentBody style={{ maxWidth: 800, margin: '0 auto' }}>
-            <EuiText data-test-subj="example-help">
-              <p>
-                This example listens for the window events and adds them to the table along with a
-                trigger counter.
-              </p>
-            </EuiText>
-            <EuiSpacer size={'m'} />
-            <EuiCodeBlock>{expression}</EuiCodeBlock>
-            <EuiSpacer size={'m'} />
-            {datatable ? (
-              <EuiBasicTable
-                textOnly={true}
-                data-test-subj={'example-table'}
-                columns={datatable.columns?.map(({ id: field, name }) => ({
-                  field,
-                  name,
-                  'data-test-subj': `example-column-${field.toLowerCase()}`,
-                }))}
-                items={datatable.rows ?? []}
-              />
-            ) : (
-              <EuiCallOut color="success">
-                <p>Click or press any key.</p>
-              </EuiCallOut>
-            )}
-          </EuiPageContentBody>
-        </EuiPageContent>
-      </EuiPageBody>
-    </EuiPage>
+    <EuiPageTemplate offset={0}>
+      <EuiPageTemplate.Header pageTitle="Partial Results Demo" />
+      <EuiPageTemplate.Section>
+        <EuiText data-test-subj="example-help">
+          <p>
+            This example listens for the window events and adds them to the table along with a
+            trigger counter.
+          </p>
+        </EuiText>
+        <EuiSpacer size={'m'} />
+        <EuiCodeBlock>{expression}</EuiCodeBlock>
+        <EuiSpacer size={'m'} />
+        {datatable ? (
+          <EuiBasicTable
+            textOnly={true}
+            data-test-subj={'example-table'}
+            columns={datatable.columns?.map(({ id: field, name }) => ({
+              field,
+              name,
+              'data-test-subj': `example-column-${field.toLowerCase()}`,
+            }))}
+            items={datatable.rows ?? []}
+          />
+        ) : (
+          <EuiCallOut color="success">
+            <p>Click or press any key.</p>
+          </EuiCallOut>
+        )}
+      </EuiPageTemplate.Section>
+    </EuiPageTemplate>
   );
 }