[Enterprise Search] Fix beta notification in sidebar (#104763)

* Fix beta notification to use flex instead of absolute positioning

- probably should have done that from the start

* Remove now-unnecessary `betaNotification*` classes/wrappers

x-pack/plugins/enterprise_search/public/applications/shared/layout/beta.scss

@@ -7,18 +7,14 @@
 
 @include euiBreakpoint('m', 'l', 'xl') {
   .kbnPageTemplateSolutionNav {
-    position: relative;
-    min-height: 100%;
-
-    // Nested to override EUI specificity
-    .betaNotificationSideNavItem {
-      margin-top: $euiSizeL;
-    }
+    display: flex;
+    flex-direction: column;
   }
-
-  .betaNotificationWrapper {
-    position: absolute;
-    bottom: 3px; // Without this 3px buffer, the popover won't render to the right
+  .euiSideNav__content {
+    flex-grow: 1;
+    display: flex;
+    flex-direction: column;
+    justify-content: space-between;
   }
 }
 

x-pack/plugins/enterprise_search/public/applications/shared/layout/beta.test.tsx

@@ -107,7 +107,6 @@ describe('appendBetaNotificationItem', () => {
         {
           id: 'beta',
           name: '',
-          className: 'betaNotificationSideNavItem',
           renderItem: expect.any(Function),
         },
       ],
@@ -118,7 +117,6 @@ describe('appendBetaNotificationItem', () => {
     const SideNavItem = (mockSideNav.items[2] as any).renderItem;
     const wrapper = shallow(<SideNavItem />);
 
-    expect(wrapper.hasClass('betaNotificationWrapper')).toBe(true);
     expect(wrapper.find(BetaNotification)).toHaveLength(1);
   });
 

x-pack/plugins/enterprise_search/public/applications/shared/layout/beta.tsx

@@ -98,12 +98,7 @@ export const appendBetaNotificationItem = (sideNav: KibanaPageTemplateProps['sol
     sideNav.items.push({
       id: 'beta',
       name: '',
-      className: 'betaNotificationSideNavItem',
-      renderItem: () => (
-        <div className="betaNotificationWrapper">
-          <BetaNotification />
-        </div>
-      ),
+      renderItem: () => <BetaNotification />,
     });
   }
 };