Remove ColumnHeader test

It's not very useful anyway

app/soapbox/components/__tests__/__snapshots__/column_header-test.js.snap

@@ -1,24 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`<ColumnHeader /> renders correctly with minimal props 1`] = `
-<div
-  className="column-header__wrapper"
->
-  <h1
-    className="column-header"
-  >
-    <div
-      className="column-header__buttons"
-    />
-  </h1>
-  <div
-    className="column-header__collapsible collapsed"
-    onTransitionEnd={[Function]}
-    tabIndex={-1}
-  >
-    <div
-      className="column-header__collapsible-inner"
-    />
-  </div>
-</div>
-`;

app/soapbox/components/__tests__/column_header-test.js

@@ -1,11 +0,0 @@
-import React from 'react';
-import ColumnHeader from '../column_header';
-import { createComponent } from 'soapbox/test_helpers';
-
-describe('<ColumnHeader />', () => {
-  it('renders correctly with minimal props', () => {
-    const component = createComponent(<ColumnHeader />);
-    const tree = component.toJSON();
-    expect(tree).toMatchSnapshot();
-  });
-});