Only select at most N runs on open

[catwell]

When you have many runs in a project, they all get selected and Trackio gets very slow.

To avoid this I limit the number of runs selected this way:

I can send a PR if you want (tests need to be modified as well).

[abidlabs]

We should solve the undelrhying issue of Trackio becoming slow, will look into it

[catwell]

If you can improve performance it's great too. I went with limiting the number of runs because usually it doesn't really make sense to compare 50 different runs on the same plot.

[sozforex]

stumbled on this issue because mlflow dashboard is too slow when hundreds of runs are shown and I hoped that maybe trackio would be better.