ref: remove react-resizable imports (#92291)

This PR removes css imports from `react-resizable`, as we don't have
`react-resizable` as a dependency in `package.json`. It’s a
pre-requisite to enable the lint rule
[import/no-extraneous-dependencies](https://github.com/import-js/eslint-plugin-import/blob/da5f6ec13160cb288338db0c2a00c34b2d932f0d/docs/rules/no-extraneous-dependencies.md).

`react-resizable` is a dependency of `react-grid-layout`, which we do
use. The import we have only adds styles for the resizable handle, which
`react-grid-layout` also adds.

I’ve tested this change on the dashboard page, and the resize handle
still looks like and works exactly like before.

I’m unsure where to find `gridPreview/index.tsx`, but I doubt that it
would behave differently.

Author: TkDodo

static/app/views/dashboards/dashboard.tsx

@@ -1,5 +1,4 @@
 import 'react-grid-layout/css/styles.css';
-import 'react-resizable/css/styles.css';
 
 import {Component} from 'react';
 import type {Layouts} from 'react-grid-layout';

static/app/views/dashboards/manage/gridPreview/index.tsx

@@ -1,5 +1,4 @@
 import 'react-grid-layout/css/styles.css';
-import 'react-resizable/css/styles.css';
 
 import GridLayout, {WidthProvider} from 'react-grid-layout';
 import styled from '@emotion/styled';