EUI Icons not rendering for some users

[scottybollinger]

Relates to https://github.com/elastic/docsmobile/issues/856

Describe the bug We have an intermittent issue where some users see a grey box where icons should be. We've held off on opening the issue because it's so hard to consistently reproduce. We now have a hacky way to at least show what users are seeing. We are still on an old version of EUI but updated our staging server with the latest to confirm the issue still exists. See below.

Impact and severity This is affecting the public facing docs on multiple pages.

Environment and versions

• EUI version: 95.1.0
• React version: 18.2.0
• Kibana version (if applicable): N/A
• Browser: Chrome
• Operating System: MacOS

To Reproduce Steps to reproduce the behavior:

1. Go to docs staging site (currently on 95.1.0 for testing) also works on live docs (not yet upgraded) in Chrome
2. Open dev tools
3. Click on the Performance tab
4. Click Record button in top left
5. Refresh the page
6. See icons broken

Expected behavior Icons render with no gray boxes

Minimum reproducible sandbox N/A

Screenshots

Video of repro steps:

https://github.com/elastic/eui/assets/1869731/eae99ffa-c4e3-4562-ba3d-ecb8945cb269

Other screenshot caught in wild. Note that even icons baked into components (dropdown arrows on left) are grayed out:

Additional context The steps to repo above is the only way we can consistently get the error to occur. We've had several users report it and have yet to have a better way to consistently reproduce. This has been reported by 5-10 users and occurs on mobile Safari as well.