[llvm] [BOLT][NFC] Add allocator id to createInstrIncMemory (PR #68709)

[Job Noorman via llvm-commits]

mtvec wrote:

> FYI instrumentation pass is not running in parallel

This really confused me but now I see that `ForceSequential=true` is passed [here](https://github.com/llvm/llvm-project/blob/416884544e0210c32c113f02c3d3881e78aac6a4/bolt/lib/Passes/Instrumentation.cpp#L557-L559).

Is it guaranteed that this will always be the case? If so, this PR isn't necessary.

Just for my information: why is `ParallelUtilities` even used if everything is executed sequentially?

https://github.com/llvm/llvm-project/pull/68709