[Popover] Fix PopoverOverlay not closing

[sophschneider]

Fixing bug where popovers weren't closing

this.clearTransitionTimeout(); was removed in #8842, this adds it back in

Before

After

Playground code

Playground code

``` import React, {useState} from 'react';

import {Popover, UnstyledButton} from '../src';

export function Playground() {
const [hoverActive, setHoverActive] = useState(false);

function handleClose() {
setHoverActive(false);
}

function handleActivatorMouseEnter() {
setHoverActive(true);
}

function handleActivatorMouseLeave() {
setHoverActive(false);
}

return (
<Popover
active={hoverActive}
activator={

hello world

}
onClose={handleClose}
>
hello world

);
}

</details>

[github-actions]

size-limit report 📦

Path	Size
polaris-react-cjs	241.16 KB (+0.01% 🔺)
polaris-react-esm	156.94 KB (+0.01% 🔺)
polaris-react-esnext	219.37 KB (+0.01% 🔺)
polaris-react-css	47.48 KB (0%)

[sophschneider]

/snapit

[github-actions]

🫰✨ Thanks @sophschneider! Your snapshots have been published to npm.

Test the snapshots by updating your package.json with the newly published versions:

yarn add @shopify/polaris-cli@0.0.0-snapshot-release-20230421234146

yarn add @shopify/polaris-codemods@0.0.0-snapshot-release-20230421234146

yarn add @shopify/polaris-migrator@0.0.0-snapshot-release-20230421234146

yarn add @shopify/polaris@0.0.0-snapshot-release-20230421234146

yarn add @shopify/polaris-tokens@0.0.0-snapshot-release-20230421234146

yarn add @shopify/stylelint-polaris@0.0.0-snapshot-release-20230421234146

[laurkim]

💯