change `Cache rate` column to `Cache hit rate`

[gruns]

Cache rate is not a standard term for caches. Cache hit rate is the correct, standard term (compare number of google results for https://www.google.com/search?q=%22cache+rate%22 vs https://www.google.com/search?q=%22cache+hit+rate%22)

• [ ] update the column header, Cache rate -> Cache hit rate

• [ ] update the column header mouseover tooltip text to use cache hit rate appropriately instead of cache rate

[gruns]

🙌