Allow New Traces Explorer to be pinned on sidebar

[makeavish]

[request-info[bot]]

We would appreciate it if you could provide us with more info about this issue/pr!

[Dessix]

I suspect the root request here is that the user doesn't want to have to click the "Try new traces explorer" button every time they click traces. Is there a compelling reason to go back to the "old" one continuously, or should it be possible to simply persist the user's selection, like with the log explorer tab?

[makeavish]

This is irrelevant as new explorer page is now default