Chore: Remove viz panel tooltip related code that is no longer needed

[kaydelaney]

This used to be needed for the new viz tooltips, but should no longer be needed now that they're portaled.

This also fixes an issue where panels lower down a page always appeared beneath ones above when being moved around.

See also: https://github.com/grafana/grafana/pull/85563

Closes #622

📦 Published PR as canary version: 4.3.1--canary.675.8546552145.0

:sparkles: Test out this PR locally via: ```bash npm install @grafana/scenes@4.3.1--canary.675.8546552145.0 # or yarn add @grafana/scenes@4.3.1--canary.675.8546552145.0 ```

[grafanabot]

:rocket: PR was released in v4.4.1 :rocket: