change arrow ui colors

[gavrelina]

align colors brightness, so that neither of them popup too much, but they look more in synch with each other and in tables.

[github-actions]

Web viewer built successfully.

Result	Commit	Link	Manifest
✅	83267bc	https://rerun.io/viewer/pr/11376	+nightly +main

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[Wumpf]

@gavrelina you need to update the screenshot tests for a change like this :)

To do so, you can run pixi run rs-update-snapshot-tests. This is expected to take quiiiite a while, especially when it hasn't been run yet. It essentially runs all Rust tests and updates any kind of snapshot file if there's a change instead of failing on discrepancies.

(as I understand Lucas is working on making it possible to do so from failed ci runs, but as of now you have to do this locally)