[Search] Adjust overlay max-height and max-width

[joshuajay]

WHY are these changes introduced?

• Adjusting the max-width on large screens helps with resolving https://github.com/Shopify/store/issues/5219

WHAT is this pull request doing?

Max-width on large screens

Reducing the max-width of the search results overlay by 6px to match the max-width of the search bar.

Before	After

Max-height on small screens

Increasing the max-height of the search results overlay so it fills the entire screen on small devices.

Before	After

How to 🎩

🖥 Local development instructions
🗒 General tophatting guidelines
📄 Changelog guidelines

Copy-paste this code in playground/Playground.tsx:

import React from 'react';
import {Frame, TopBar} from '../src';

export function Playground() {
  const searchResults = (
    <div
      style={{
        backgroundColor: 'white',
        height: 3000,
      }}
    >
      Test results..
    </div>
  );

  const topBar = (
    <TopBar
      searchField={<TopBar.SearchField value="Test.." onChange={() => {}} />}
      searchResults={searchResults}
      searchResultsVisible
    />
  );

  return <Frame topBar={topBar} />;
}

🎩 checklist

• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility
• Updated the component's README.md with documentation changes
• Tophatted documentation changes in the style guide
• For visual design changes, pinged one of @ HYPD, @ mirualves, @ sarahill, or @ ry5n to update the Polaris UI kit

cc/ @benluii

[dleroux]

🎩 in web. Works as expected.