What does this PR do?

Fixes an issue where the SelectMultiple drop would scroll back to the top after selecting an option.

Where should the reviewer start?

What testing has been done on this PR?

Tested with the following story:

import React from 'react';

import { Box, SelectMultiple } from 'grommet';

const dummyOptions = Array(100)
  .fill()
  .map((_, i) => `option ${i}`)
  .sort((a, b) =>
    a.localeCompare(b, undefined, { numeric: true, sensitivity: 'base' }),
  );

export const Test = () => (
  <Box gap="large" fill align="center" justify="start" pad="large">
    <SelectMultiple
      options={dummyOptions}
      showSelectedInline
      placeholder="select an option..."
    />
  </Box>
);

Test.args = {
  full: true,
};

export default {
  title: 'Input/SelectMultiple/Test',
};

How should this be manually tested?

Do Jest tests follow these best practices?

• screen is used for querying.
• The correct query is used. (Refer to this list of queries)
• userEvent is used in place of fireEvent.
• asFragment() is used for snapshot testing.

Any background context you want to provide?

What are the relevant issues?

Closes #6709

Screenshots (if appropriate)

Do the grommet docs need to be updated?

No

Should this PR be mentioned in the release notes?

Yes

Is this change backwards compatible or is it a breaking change?

Backwards compatible