Ecosystem: hide qiskit-ui-shell

[Eric-Arellano]

I was thinking we can simply set display: none in the CSS to keep things simple and avoid changing the HTML template page.html. But confirm this is accessible for e.g. screen readers.

We also need to update the JavaScript here:

https://github.com/Qiskit/qiskit_sphinx_theme/blob/10fff40263d084e9f09fde008914b3aea31730a5/src/qiskit_sphinx_theme/assets/scripts/qiskit-sphinx-theme.js#L147-L150

We could do this by dynamically checking if qiskit-ui-shell is defined, or maybe if its display is set to none, and set to 0 if so.

[Eric-Arellano]

Everything looks good in https://github.com/Qiskit/qiskit_sphinx_theme/pull/469 except for weirdness with the left side bar.