[ic-search-bar/ic-menu] external data filtering and loading bug

## Summary of the bug
When data is brought back to search-bar on a promise (mocked api for testing in storybook) the menu is not automatically opened until another keystroke is entered

## 🪜 How to reproduce
See tickets #1939 and [#1919 comment](https://github.com/mi6/ic-ui-kit/pull/1919#discussion_r1618358266) for info on reproduction.

## 🧐 Expected behaviour
When data is returned to the search bar it should open with the results directly, rather than waiting on further input.

Start by inspecting the ic-search-bar and ic-menu entry points and review tickets #1939 and the linked #1919 comment for the reproduction details. Verify the promise-based data flow in Storybook and consider the work complete when returned results open the menu immediately without another keystroke.

Written by the indexing model from the issue text.