ASV: remove large IntervalIndex benchmark
Closes #26709

The `setup` for that `N` took 30s+ on my machine. I doubt that was intended.
Hmm travis is not happy. Any objections to me merging this, and following up with CI fixes for travis? @TomAugspurger a travis build failed, but can't see how to re-run (I used to do it, not sure if travis changed something)

I also see that the doc build is failing, I'm taking a look, it was failing because this PR I'd say that the job failed because the pytest processes were killed, looks like a server problem to me.

Happy to get this merged as it is.