[KibanaPageTemplateSolutionNavAvatar] Increase specificity of styles

[cchaos]

Mostly a temporary fix until #132363 is figured out

Since EUI switched to Emotion, we've converted just a few components like EuiAvatar. But there's a slight import of styles ordering issue that causes some custom Kibana styles to not override EUI's styles because of cascade order. This one I just fixed specifically by increasing the specificity for the stylized xxl version.

BEFORE

AFTER

Checklist

• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 44c0ef3
• Storybooks Preview
• Webpack Bundle Analyzer

Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
kibanaReact	59.6KB	59.7KB	+66.0B

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream