Fix page layouts, clean up unused code (#63992)

Author: jen-huang

x-pack/plugins/ingest_manager/public/applications/ingest_manager/layouts/default.tsx

@@ -20,8 +20,6 @@ interface Props {
 const Container = styled.div`
   min-height: calc(100vh - ${props => props.theme.eui.euiHeaderChildSize});
   background: ${props => props.theme.eui.euiColorEmptyShade};
-  display: flex;
-  flex-direction: column;
 `;
 
 const Nav = styled.nav`

x-pack/plugins/ingest_manager/public/applications/ingest_manager/layouts/with_header.tsx

@@ -10,8 +10,6 @@ import { Header, HeaderProps } from '../components';
 
 const Page = styled(EuiPage)`
   background: ${props => props.theme.eui.euiColorEmptyShade};
-  flex: 1;
-  align-items: flex-start;
 `;
 
 interface Props extends HeaderProps {

x-pack/plugins/ingest_manager/public/applications/ingest_manager/layouts/without_header.tsx

@@ -9,8 +9,6 @@ import { EuiPage, EuiPageBody, EuiSpacer } from '@elastic/eui';
 
 const Page = styled(EuiPage)`
   background: ${props => props.theme.eui.euiColorEmptyShade};
-  flex: 1;
-  align-items: flex-start;
 `;
 
 interface Props {