Remove wrapped StyledPageTemplateComponent

Since elastic#146212 we use a development build of React. This has surfaced
some existing problems in the `UptimePageTemplateComponent`, namely a
`useMemo` hook that was calling other hooks inside it by caching a
component.

The wrapped component seems to have some extra styling for mobile users.
For now we will remove this change to make the Uptime plugin work again
and tackle the issues with mobile rendering in a different PR.

x-pack/plugins/synthetics/public/legacy_uptime/app/uptime_page_template.tsx

@@ -5,8 +5,7 @@
  * 2.0.
  */
 
-import React, { useEffect, useMemo } from 'react';
-import styled from 'styled-components';
+import React, { useEffect } from 'react';
 import { EuiPageHeaderProps, EuiPageTemplateProps, useIsWithinMaxBreakpoint } from '@elastic/eui';
 import { useKibana } from '@kbn/kibana-react-plugin/public';
 import { useInspectorContext } from '@kbn/observability-plugin/public';
@@ -22,12 +21,6 @@ interface Props {
   pageHeader?: EuiPageHeaderProps;
 }
 
-const mobileCenteredHeader = `
-  .euiPageHeaderContent > .euiFlexGroup > .euiFlexItem {
-    align-items: center;
-  }
-`;
-
 export const UptimePageTemplateComponent: React.FC<Props & EuiPageTemplateProps> = ({
   path,
   pageHeader,
@@ -37,18 +30,8 @@ export const UptimePageTemplateComponent: React.FC<Props & EuiPageTemplateProps>
   const {
     services: { observability },
   } = useKibana<ClientPluginsStart>();
-  const isMobile = useIsWithinMaxBreakpoint('s');
 
   const PageTemplateComponent = observability.navigation.PageTemplate;
-  const StyledPageTemplateComponent = useMemo(() => {
-    return styled(PageTemplateComponent)<{ isMobile: boolean }>`
-      .euiPageHeaderContent > .euiFlexGroup {
-        flex-wrap: wrap;
-      }
-
-      ${(props) => (props.isMobile ? mobileCenteredHeader : '')}
-    `;
-  }, [PageTemplateComponent]);
 
   const noDataConfig = useNoDataConfig();
 
@@ -69,8 +52,7 @@ export const UptimePageTemplateComponent: React.FC<Props & EuiPageTemplateProps>
 
   return (
     <>
-      <StyledPageTemplateComponent
-        isMobile={isMobile}
+      <PageTemplateComponent
         pageHeader={pageHeader}
         data-test-subj={noDataConfig ? 'data-missing' : undefined}
         noDataConfig={isMainRoute && !loading ? noDataConfig : undefined}
@@ -84,7 +66,7 @@ export const UptimePageTemplateComponent: React.FC<Props & EuiPageTemplateProps>
         >
           {children}
         </div>
-      </StyledPageTemplateComponent>
+      </PageTemplateComponent>
     </>
   );
 };