Removed unused Popover component

public/app/core/components/Tooltip/Popover.test.tsx

@@ -1,16 +0,0 @@
-import React from 'react';
-import renderer from 'react-test-renderer';
-import Popover from './Popover';
-
-describe('Popover', () => {
-  it('renders correctly', () => {
-    const tree = renderer
-      .create(
-        <Popover className="test-class" placement="auto" content="Popover text">
-          <button>Button with Popover</button>
-        </Popover>
-      )
-      .toJSON();
-    expect(tree).toMatchSnapshot();
-  });
-});

public/app/core/components/Tooltip/__snapshots__/Popover.test.tsx.snap

@@ -1,16 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`Popover renders correctly 1`] = `
-<div
-  className="popper__manager test-class"
-  onClick={[Function]}
->
-  <div
-    className="popper_ref "
-  >
-    <button>
-      Button with Popover
-    </button>
-  </div>
-</div>
-`;