Fix ref panel action button

Created by: oleggromov

Description

Addresses https://github.com/sourcegraph/sourcegraph/issues/39517.

https://user-images.githubusercontent.com/2196347/185104853-3912163e-812f-467f-9c5c-7a0476db5b26.mov

Test plan

1. Pull the branch
2. Pull the branch from code-intel-extension: https://github.com/sourcegraph/code-intel-extensions/pull/821
3. Run yarn serve in code-intel-extensions
4. Run sg start web-standalone
5. Sideload the extension with default parameters
6. Check that it works as expected

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.