CI/BENCH: Make CategoricalIndexIndexing benchmark less flaky
Resizing `data_unique` to be the same length as `data` which maybe is some source of flakiness since `data_unique` was 3x `data`

I'll merge in main maybe 2 more times just to confirm.  might be quicker to just re-run the code-checks jobs

![image](https://user-images.githubusercontent.com/33491632/204044360-b5bbe815-2264-442a-b426-1a5c54779ac8.png)
 I restarted the job and it still passed, so let's ship this, if it fails again we can revisit. Thanks @mroeschke !