[llvm] [BOLT][heatmap] Produce zoomed-out heatmaps (PR #140153)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis commented:

Great option! It may be worth listing this in the [Heatmaps.md](https://github.com/llvm/llvm-project/blob/main/bolt/docs/Heatmaps.md), alongside the suggested usage.

> Suggested values to use: 4096 (default page size), 16384 (16k page),
1048576 (1MB for XL workloads).

https://github.com/llvm/llvm-project/pull/140153